Sam has figured it out to where it could be a science. He knows the exact time frame, behaviors, and attitudes that define it. He could tell you precisely when it begins and ends. And he could also tell you that if he brought it up to his big brother, that brother would be quite creative in the insults that would be hurled his way.
Sam's brother, on the surface, is a very simple man. He enjoys eating, making crude remarks, and occasionally an odd strip club or two. He can be a very happy man with a cheeseburger in one hand and the remote in the other. However the delicate balance that Sam has found controls his life is much more complex and cannot be solved by a mere cheeseburger.
After many years of being the victim of its abuse and privileges Sam has learned the necessary steps that must be taken in order to ensure an equilibrium for a more...agreeable Dean.
He knows that the first week after a hunt is the most enjoyable for both brothers. Tensions and tempers are wound down after the hunt has been successfully completed. There is downtime- with the recovering from the hunt and not yet starting to search for a new one. Dean most likely will enjoy this time by shoving many various diner foods down his throat. Alcohol and adult entertainment, to list some of the 'A's' are just a few of the fun things that Dean racks up bills on this week, of course all in "slue of celebration, Sammy." Sam also knows that this is the best week to ask for a favor and expect a rational response. If Sam were to say, need to borrow the Impala for a recreational activity, this would be the best time to ask...even though he would fully expect the answer to be 'no'. However these are also the days the Sam might be referred to as "professor, Samantha, or Sam-kins", all to Dean's good mood and Sam's dismay.
The second week brings about a great change in the subject. Dean has grown tired of slewing about in the room. He begins complaining about the "poor quality" of the adult entertainment channels and almost cringes as he crunches on his depleting stockpile of Funyuns. It's this time that Sam urges Dean out of the room because he cannot bear to hear another tale about Tanya from Maine- who sprung him into the next morning, "if you get what I'm saying." Sam uses this time to search for a case because he knows no work will get done while horn-dog Dean is around. Late at night usually finds Sam in a library because he has witnessed the horrors of what Dean does in there hotel room at this time and wishes to never subject his eyes to that kind of monstrosity again. This is the week that Sam may bring home a Maxim magazine and absently hand it over to Dean all while broaching the touchy subject of borrowing the Impala. Depending on the interest Dean takes in this magazine, sometimes Sam is told "Yes."
Sam dreads week number three, mostly because he is the innocent victim of it. It's a slow progression but one that usually sends Sam storming from the room in a fit of anger. Seeing as Dean has used the previous week to satisfy his, "manly desires", he has now become restless and has moved on to doing what only an older brother can do so absolutely relentlessly, annoy the hell out of there younger siblings. It always starts with an innocent whistle, sooner or later it will progress to the humming of a Metallica song, and just like that Dean has shamelessly been singing "Stairway to Heaven" for the past two hours. Sam, as a younger brother must so often do, makes the crucial decision of ignoring Dean. Seeing his brothers tense shoulders and once again, taking it upon himself to do what only a brother can do, Dean uses this time to slowly gnaw away at his brother's composure with sly remarks, crude cleanliness habits, and dietary intake. Eventually, when Sam can no longer take it, he demands that Dean give him the Impala keys. Dean breaks the final straw with a amused smirk and a simple remark, "no."
Week four is always a frustrating week for Sam. After spending the previous weeks researching and preparing for the next hunt Sam is usually left in the dark. Dean, despite Sam's suggestions, has found a better hunt and "that's all there is to it." Sam grudgingly drags along as Dean orders him to "pack your crap", "get in the car", "stop being a bitch". He knows this is just how Dean operates before a hunt, all bossy and demanding like, it sucks but he's used to it. Every once in a while, because they are trying to kill a ghost or stop a raging mad witch, Sam get's to drive the Impala without even asking. It's never as great as he expected, being in the Impala without Dean, because he's more focused on usually trying to save someone from dying or dramatic stuff like that.
Sam's lived it, Deans ways- so predictable. He could teach a college course on it, Dean-ology 101. He's like a hormonal women flip flopping week to week. Cool and collected, total sex addict, annoying like a mosquito you can't seem to kill, to the bossiest person ever. It's not exactly Sam's ideal but why the hell should Sam expect normalcy out of his completely un-normal life. What fun would that be?
Sam wasn't even mildly surprised as Dean came barging through the hotel room caring two grocery sacks of brightly colored packages of snack food. Guess it's just that time of the month again...