Used to mock people who are worse than you in anything or are bad at something. The word 'Frag' is a term used in early fps ,such as Doom(1993), as slang for a players net kills ( number of kills - number of deaths).
Person 1 :"I just failed my maths GCSE" Person 2 "LMAO Frag harder scrub"
" Get domed, frag harder scrub!"
Masturbating a guy with smegma, dick cheese, etc. or any other strong smelling substance.
There's no lube, but your dick cheese is slimy, I'll just use that! That's nasty you pig scrubbing bitch! Use spit!