The "who" actually functions as the subject there, which together form the object of your laugh. Like, I saw [the man who robbed the bank].
But anyway, I think you're fine without any punctuation at all. If you wrote "who want to go to the same schools I do, yet who take every AP course offered," you'd be fine as well. In fact, it's less ambiguous.
Your original sentence could be read as "I laugh at... yet I take every AP course offered" instead of "I laugh at my friends who want... and who take."