When there are no plus ones and two mates are 'loosely invited' bringing only a small box of booze as an offering, I felt sorry for the host. But we got ourselves into his house party surprisingly early so we couldn't disappear off and had to smooch our way in and drinking a lot of free booze helped. Though not going to the same school the host ended up fine with my company as a lot of people from their school recognised or knew me. Definitely worth it especially when people thought I knew the host well I had constant conversation. I will gate crash more parties in future though I will bring a greater box of booze not to feel guilty.