endgame begins at the end of the senior year of college or high school. endgame is played between all of the seniors. the point is that since you are graduating soon now is the time to hook-up with anyone and everyone you ever had a crush on, no regrets! the people the seniors endgame don't have to be in the senior class. often it is a competition to see how many endgames one person can get. the best type of endgame is a game-changer when a senior hooks up with someone completely unexpected (i.e. a freshman, someone of the same gender, or their best friend).
Senior 1: Yo man how's your endgame going?
Senior 2: Well I got one endgame at a party last night and I still have a few more on my list. Remember that girl from that class freshman year?
Senior 1: Yeah dude she was so hot! Totally endgame that!
Senior 3: Did you hear about Bob's end game last night?
Senior 4: No! What happened?
Senior 3: He hooked up with his best friend Sally! That girl is so hot and way out of his league!
Senior 4: No! That is such a game-changer, Bob is going to win the endgame!