Maybe he's sensitive because of his history, but Puck hates the term "unplanned pregnancy". It makes him sound like a teenager. He's a grown man in a committed relationship with a woman that he loves (and no he's not too much of a pussy to admit that). He and Rachel may not have planned their son but that doesn't mean that he isn't loved or wanted or everything that every baby should be.
So it really pisses him off that his mom (who's practically been poking holes in his condoms since he started dating Rachel) keeps using that term. She loves Max to bits, but it's her way of making it known that she wishes he and Rachel were married.
Ideally, they would be. He's known since their second date that he was going to marry her someday. They've talked about it (long after that second date), but they were focusing on their careers and figured they would have lots of time to get married. Once they were pregnant, they didn't really want to rush around trying to plan a wedding when they had more important things to think about.
But Max is almost a year now and the way Puck looks at it, there's always going to be a reason not to get married. He wants to make an honest woman of her.
So the next time they go home to Lima to visit the parents, he takes the ring he's had for a lot longer than he'd like to admit.
He has a couple of kickass ideas about how to propose. He thinks about taking her to the bleachers at the school where he first admitted that he liked her more than he should, but it doesn't feel right. In the end, he thinks using the baby is the best idea.
Rachel usually feeds Max while Puck is in the shower, and then Puck gets Max dressed while Rachel is in the shower. He talks to his son as he dresses him in the little white onesie, the green hooded sweater his sister made for Max, and his little jeans (you don't know cute until you dress a baby in a tiny pair of jeans). Then he and Max head downstairs to hang out with his mom and sister and wait for Rachel's dads to show up.
No one has any idea what he has planned except Max, and the kid isn't going to spill the beans. Right on schedule, Max has his daily poop and needs to be changed. The whole family looks at him like he's crazy when he insists that Rachel change Max, even though his mom offered.
Puck is waiting for the squeal of joy to come down the stairs, but instead Rachel huffs back into the room with a half-dressed Max, the 'Mommy, will you marry Daddy?' clearly visible on the front of his onesie, and thrusts him into his arms before turning on his mom.
"Debbie, I honestly can't believe that you would stoop so low as to use your grandson in an attempt to trick me into thinking that Noah had proposed." Puck pulls the ring box out of his pocket and opens it, making sure to keep it far away from Max (kid likes shiny things). Every eye in the room, except Rachel's, is on the box in Puck's hand. "Noah and I will get married when we feel like it, not a moment sooner. And why are you looking at me like I'm crazy?"
"Babe." Rachel whips her head around and her mouth pops open in surprise.
"Oh!" He moves to a standing position, Max squirming in his arms.
"Rachel, will…"
"Yes!"
"You didn't hear the question." Puck chuckles, passing Max off to Rachel's dad.
"I read the shirt." He takes her hand in his and slides the ring on her finger before kissing her.
"Honestly, if I had known a t-shirt was all it would take…"