Furries are playful.
Fapping is playful.
Foreplay is playful.
Farting is playful.
Faking an orgasm is playful.
Fantasizing is playful.
Funking is playful. (And, if you DON'T know what "funking" is, look it up for yourself. Seriously, do I have to do EVERYTHING around here!)
Funyuns are playful.
Fisting is playful. (I mean fist-bumping, you pervs!)
Fingering is playful. (Yes, I mean THAT kind of fingering, you pervs!)
Falafels are playful. (Just ask Bill O'Reilly!)
Fondling others is playful. (Just ask Donald Trump!)
I would say fishing is playful but, you know, it's fishing!
And, finally, flipping the bird is playful.
I bet you thought I was going to say "f*cking is playful", didn't you? (Sorry, you pervs!)