Similar to TGIF, HSIF is an Acronym for "Holy shit it's Friday". Used when someone just comes to the realization that the day is Friday and need to plan for the weekend.
Student: I have to do all this work for tomorrow.
Friend: Why? It's Friday, you have 2 full days.
Student: HSIF, is anyone having any shindigs going down tonight?
Friend: Why? It's Friday, you have 2 full days.
Student: HSIF, is anyone having any shindigs going down tonight?
by Weasel C. November 6, 2009