What does #ff on twitter mean?

[gerryhanlon2000]

Just wondering!

[Yassar Ilyas Khan]

The Hash tag (#) followed by a word or any number of words represents a trending topic. The trending topic is what everyone is talking about on any particular day.

[melodicrobin972]

ff means user allow to follow you.

[KirstyTMB]

the ff stands for 'Follow Friday' then people just hashtag it (#)
Basically people suggest other people to follow and it always happens on a friday, hence the name 'Follow Friday'

[Wendigo]

The category you posted this in is for MySpace, and not for Other - Internet. For future reference check the category that is being suggested, as the category can be wrong, as has happened on numerous occasions. By checking that, you will have a higher chance of getting an accurate answer to your query.