Well..at my school the girls usually ask the guys for their jersey, unless they are going out. Then they were their boyfriends jersey
Compliment her or say something like "I would love it if the prettiest girl at school wore my jersey" (: honestly if any guy asked me to wear his football jersey I wouldn't say no
"Hey so it's kind of a team tradition that the football players girlfriends wear their jerseys on gameday, and I thought I'd be cute if you could wear it on Monday?" *smile* IT IS SO CUTE THAT YOU WANT HER TO WEAR YOUR JERSEY, DONT LET HER SAY NO! :D
1st off its not football season :(. anyways just bring the game up in a conversation and be like "hey do u wanna wear my jersey?" be casual
If she likes you tOo then just ask and she should not mind it at all
