Warning: NSFW!
Here are some hilariously funny but rather offensive expletive names to call people who insult you. Why settle for the norm? Responding with "a$$hole" or "jerk" is just boring. You are more likely to gain respect if you respond with something the attacker has never heard before! Any of these will do.
ass goblin
cum bubble
Fuck nut
fuck ball
schmuck
Shit pisser
stank face
shaft sock
blowhole
fuckwit
douchewaffle
vomit fondler
jerk tard
ebola pussy
putzy shit sample
thunder cunt
useless moron
cum knob
queef master
shit sprayer
shit stack
Cum Guzzeler
pathetic parasite
chicken shit
turd licker
fuck stain
shit brick
pap smear
degenerate
cock smoker
cunt sack
useless loser
man whore
moose cock
fuck stick
Bowl of ass soup
douche tard
jizz bucket
ass maggot
ass clown
butt moocher
douche sucker
vaginal bloodfart
piece of cum cake
hose monster
cunt bag
scrotum breath
cum shot
shit licker
sperm dumpster
brainless waste of space