For the Fiesta Bowl last year, I believe it worked like this: if you are a student and a season ticket holder, you are then eligible to enter a lottery. If you win the lottery, you pay for the ticket (face value) and receive a voucher which you use to claim your ticket at the bowl game location (i.e. you pick up your game ticket at the will call of the bowl game stadium). You can only use your voucher to claim your ticket. In other words, if your friend wins the lottery and can't go, you CANNOT take his/her voucher and go to the bowl game expecting to get a ticket because they will ask for matching photo ID and whatnot. The ticket office usually holds a second or third lottery after the first one, drawing from the pool of rejected vouchers (i.e. students that win but can't go to the game).
I'm not 100% confident that is the way it works because the past two years I've been very unlucky and have had to shell out some serious dough for bowl game tickets. Hope that helps!