What is a good punishment for your boyfriend?

Its not that my boyfriend is bad or anything, hes just not trying hard in school and i want him to do better to get into college, he has a 58 average and i worry he wont get in. I am encouraging him to get a 70 average which isnt hard for him since he did take an iq test before and his iq is above average its just that he doesnt try. So if he tries he will be able to get atleast a 70 average. I told him if he did he gets a reward, but if he didnt he would get a punishment, what should the punishment be? My first choice was he couldnt kiss me for the whole summer, and he said that i wouldnt be able to handle that myself. I want a punishment that will encourage him to try hard in school but something that wouldnt punish me as well. Any ideas? Thanks.