There is a simple trick, which you can easily play almost at every party.

If a person gets drunk on your party, you have all rights to play a trick on him!
So, if he suddenly falls asleep, he immediately becomes a perfect victim
At my parties I usually practice the following- I bind his laces! When he wakes up, it is quite difficult to stand up!

Or there was also a funny case once, when a person fell asleep at the party and we decided to have fun. We tied his laces to the bed, and tried to do the same with his clothes!
We had a perfect morning that day

Hope the idea will be helpful for you! Have fun!