The day you successfully fill your girlfriend with a total of one gallon of cum (1,000 deposits) during your relationship
“Hey man have you done the homework?”
“Nah. I’ve been trying really hard to reach gallontines day”
A holiday celebrated on February 14th by eating an entire gallon of ice cream.
Allison: "Happy Gallontine's Day Nicole! Would you like to come over and celebrate by eating an entire gallon of ice cream?"
Nicole: "Do we have to share a gallon of ice cream between us?"
Allison: "Don't be silly! We EACH get to eat a gallon of ice cream, as the tradition goes of course."
Nicole: "Sounds great! I'll be sure to wear sweat pants!"
A holiday celebrated on February 13th by drinking a gallon of beer.
Chad: Bro, are you celebrating Gallontine's Day this year?
Jason: Yeah brah, got my PBR.