any substance, alcohol or otherwise, that enhances a party. similar to performance enhancing substances in the fact that they are sometimes illegal, and that many people are against them(depending on age).
my good friend captain morgan is a party enhancing substance
mike snuck us in some party enhancing substances in his flask
the party was pretty lame, then we got some party enhancing substances and found the trampoline
He cannot stop staring at her. My God. She is so incredibly beautiful. He stands frozen at the top of the escalator, people pouring off it right behind him, tripping and falling. He dimly realizes that he is being prodded, cursed and yelled at to MOVE! yet he remains entrancegent.