Pestilence is commonly refereed to as being poured, i.e pouring pestilence.
A pestilence party is the large scale pouring of friend pestilence, which can occur with or without the target being present.
Friend 1: jeez i poured some great pestilence there last night!!
Friend 2: so your in mate, you'll have her in no time!
Guy "pours friend pestilence". The friends of the target think he/she is really nice and recommends him/her to the target.