Tee Eff (tf) is something you say when something is absolutely ridiculous or unexpected. When your grandma only gives you $5 for your birthday, you typically say "Tee Eff?!" You then reach in the bag to grab the AK-47 to ruin her day. Other uses for "Tee Eff" would be if an ugly girl slides in your dm's. The right the to do is send a screenshot to your homeboy and ask "Tee Eff?!". Tee Eff is just used to emphasize the letters "T" and "F" in the popular "Tf" abbreviation for "The fuck".
Patrick: "Bro, I wish I had a bald girlfriend so when I have sex with her from the back I can smack her baldy."
Owen: "Tee Eff???!!"
A way of writing out the ever-so-popular Internet acronym "WTF" which stands for "What The Fuck". It is usually used to be funny, to exaggerate, or be very sarcastic. This method can also be used for any other acronym:
LOL - ell oh ell
ROFL - ARE OH EFF ELL
OMG - oh em gee
It has also been known that WTF has been pronounced like "wuh-tff" when people try say it like it's spelled, as they would say "Lawl" or "Rawffle" in lieu of LOL or ROFL.