It means you asking someone what is the temperature outside or inside. Can be "What's the C" for Celsius areas. (Or even K, if you wanted.)
Response ends with the actual temp. but you just say the number and 'F' at the end.
Synonyms for What's the F?
On this page, you will find 30 slang terms related to What the f. Some of the top words include: Hot as balls, weatherical, brick, brrrh, skizzy, and 25 more.
