Many people use it as a nickname.
Some even use avatars/signatures of it in forum]s, a blue logo of Firefox - so easy to create in Adobe® PhotoShop]® or in any image editing tool that allows recolouring (like PhotoFiltre], PhotoFiltre Studio X] and GIMP]).
Dumb Person no. 2: I prefer Firefox.
Smart Person: OMG, you dumbass]es, Waterfox is a "blue" fan-art of Firefox.