Twenty one ways to piss off Sentinel Prime.
Thanks for all the R&R's. ironfire 13 and Firestar 1999 get credit for two ideas.
Disclaimer: Hasbro owns Transformers.
Idea number seven: Sneeze on him.
Sentinel is scared to death of all organic things; especially things that come from organics. Ever seen Peanuts Lucy freak out when Snoopy licked her? Well, guess who's a big robotic version of that. All he needs is a femme frame and he's a dead ringer. To pull this off perfectly, inhale some pepper and call Sentinel down to eye level. When he asks in his very snobish way what you want, sneeze right on his faceplate and reply "a tissue." Immediately get clear as S.P will freak out and maybe accidentally (or so he'll claim) flatten you.
Idea number eight: A cold shower.
When Sentinel go's to the wash racks, replace the cleaning solution with liquid nitrogen. The moment it hits our idiot victim, it will freeze entraping Sentinel (or at least his head) in an ice cube. Normally it would take a few hours to melt off, but it's likely he'll be so pissed his core temperature will melt it off in less than ten minutes. Take that time to set up another prank or dawn some armour of your own.
Idea number nine: Keep it green.
Get into Sentinels room and line it from one end to the other with Earth plants. Weeping willows, venus fly traps, assorted flowers, the whole nine yards. Dandelions in their fluffy form are especially annoying. Sentinel will have a mechanical bull when he sees what you've done. For days after, he'll probably have his armour upgraded into hazmat and his face plate up constantly. This prank is good if you like the space he had due to the fact he'll never want it again. It's a win-win for you. He's tormented and you get a new room out of it.
Another addition to his agony courtesy of prankers everywhere