It seems like there are a limited amount of activites you can do with an ESFP. Stereotypically they include: performing musical activites (like performing a song the ESFP wrote out of some sappy poetry journal entry of theirs) at a local coffeehouse, raving, sex, sharing feelings, crying, going clubbing
With an INTP: Studying for a test (age irrelevant, all INTPs will take forever to complete school due to their innate ability to be without learning), conversing strongly about a political topic with no mercy finding fallacies in every arguement sometimes taking devil's advocate just because they can, playing chess, lounging around in their house until they run out of food or have to go to work/class --- essentially avoiding all human contact, cleaning their glasses since I assume most INTPs wear um' since they read so many text books.
Now, they could attempt to share the act of sex, but INTPs don't have sex. They are simply too interested in knowledge and detached from things. I have absolutely no idea why an ESFP would like an INTP, besides perhaps fansination that will melt when they realise they don't understand 95% of what the INTP is babbling about ( probably some scientific theory explained in math formulas) and an INTP would be tramatized if they went out clubbing with the ESFP, most likely being mauled by people that are lovin the E.