Used as a replacement for any word.
It is for the person that says it to decide its meaning.
Check out my fert! (CHeck out my ass, boobs, shirt, pants etc etc etc)
Dont fert! (Dont sweat it)
Look at your fert (look at ur face etc etc)
FERT (any thing that exclaims a surprise like cool wow awesome etc etc
Prices shown in USD.