(games) Initialism of capture the flag. / (inorganic chemistry) Initialism of chlorine trifluoride. / Initialism of counter-terrorist (or terrorism) financing.

(Internet) Initialism of chill the fuck out.

(chemistry) Abbreviation of chlorotrifluoroethylene. / (programming) Initialism of compile-time function execution.

(Internet slang) Initialism of cracking the fuck up.

(Internet slang) Alternative letter-case form of CTFU

(software, testing) Initialism of Certified Tester Foundation Level.