Dick: Wakes up at 3am to sneak into Tim’s apartment and wake him up by screaming “HAPPY BIRTHDAY, TIMMY!!” at the top of his lungs and gets knocked out when Tim reflexively punches him in the face
Barbara: Bakes his favorite cake and calls up everyone in the batfam and orders them to wish Tim a happy birthday or she’ll kill them
Jason: Calls at some point to wish Tim a happy birthday and also to inform him that he hid a confetti bomb somewhere in Tim’s apartment but doesn’t remember where, so if it blows up at some point and it rains birthday confetti everywhere then just know that that was from Jason
Tim: Forgets until somebody has to remind him
Cass: Won’t stop hugging him the whole day and gets him really sweet gifts because she’s a literal angel
Steph: Is as excited as Dick and insists on taking Tim out to do fun birthday stuff all day, and when they go to dinner she tells the waitress that it’s Tim’s birthday so the staff all sing happy birthday to him because she knows how embarrassed he gets
Damian: “I got you a rock” “What, why?” “How dare you! I’ll have you know I picked this out specifically for you. God, you’re so ungrateful”
Just in case nobody knew this but in Civil War when Tony calls Peter “underoos” it was not only a jab at his spandex-type uniform but a reference to the 70s children’s underwear “underoos”. It was popular for kids to get these to play dress up in so basically Tony compared him to a kid playing make believe in his underwear.