I wasn't aware you could have intercourse in any mass effect until 3, and I still don't know how, and I didn't know you could have sex in dragon age: origins until my 3rd playthrough. Boy, was that a weird surprise 
EDIT: I also didn't realise for like 8 hours that in dead rising 2, saving survivors makes you level up like mad. I thought they were just for achievs (which I don't really care about).
EDIT: I also didn't realise for like 8 hours that in dead rising 2, saving survivors makes you level up like mad. I thought they were just for achievs (which I don't really care about).