When it’s Friday, as a casual greeting, you can say “Hey, how are you? TGIF!” (pronunciation: TEE-GEE-AI-EFF)

It means “Thank Gosh It’s Friday.” It’s a very casual phrase, so use it in the appropriate setting! This phrase is very common in American offices among colleagues who are the same level．It might be best to not try this phrase with your boss, unless you have a friendly relationship!

Example:

A: Hey Tom, TGIF! Got any plans for the weekend?

B: I’m going to have a barbecue with the family, as long as it doesn’t rain!