A post on a social media thread, or private conversation, in which the person posting satirizes common elements of other people's posts by making it too weird or outlandish to be serious.
This can be overt, or subtle, but the highest quality roast post tricks you into believing it might be a real post before the roast becomes clear.
A Roast Post In the context of a work sack channel on a day that an important report is due:
"Did everyone get a chance to checkout the TPS report?"
- TPS report being a reference to the meaningless reports the characters in Office Space were forced to file
For someone to diss you/mock you based on a characteristic of yourself, your personality, clothes etc. in front of a lot of people
Example of a Roast Whipping Post:
Teacher: Ok Class, that's the bell everyone is dismissed. Stacy, please see me after class.
Stacy: Why? Can't get a date for prom?
Teacher: If that was the case I would've asked one of the pretty girls.
Class: DAYUM!!!!