To chat with an Old friend who you have not been in contact with for a while.

To catch up from the times they haven't seen each other.

to drink an excessive number of shots rapidly in order to be as drunk as your peers.

pub reunion and forgiveness to the insulter.

This is when a sporting event ends and they start catching you up on what had happen during the game.

pub reunion and forgiveness to the insulter.

'DVD catch-up' is when, while recording a game or other TV event on your DVR, you start watching the recording from the beginning - and as you come to the ads, timeouts, etc., you fast-forward through them, thus slowly catching-up on the event in real time.