I have been to a party with a friend at his house and wore a diaper.
I danced and moved around a lot and nobody noticed that I had a diaper on.
I wore a Teddy Bear Bambino Diaper and wet it and even pooped it during the party and nobody noticed or just wasn't paying attention.
At a party everyone is so busy partying and having fun that they are not likely to notice a diaper.
I've been to bars wearing a thick diaper too and it was great just peeing in the diaper while I drank some beer.