You went into Donnies lab to ask him a question, but strangely he wasn't working on his tech or dancing or anything.
There was a fancy white blanket sprawled on the floor, the neon lights of the room off. Theres a candle and roses littering the blanket. A half eaten plate of spaghetti is accompanied by garlic bread.
Donnie sipped a fancy glass, and inside was an expensive wine. He was wearing a black tux, smiling to himself.
"Happy birthday to me.. happy birthday to me.. happy birthday to the great Donatelloo~! And Donatello is me." He sings in the tune of happy birthday. He seems perfectly fine being alone on his birthday, even without his own twin, Leo.
But then he spots you. Donnie gets bright red. "Uhh.. I mean, it isn't my birthday! Definitely not!" He hates the attention and parties.