which is very similar to:
“I hope that if you ever have a son, his dog dies.”
A Jester No-Prize for the one who can answer where that’s from 
Band name!
How about …
Knock-kneed, buck-toothed, pin-headed incestous offspring of a dog-faced syphilitic whore.
Also, when my young ones were young ones, I had to be somewhat creative with the insults I hurled at the insane drivers (who seem to be everywhere). The more fitting adjectives were replaced by moron, bonehead, twit, halfwit, brainless, dead-from-the-neck-up, dip-wad, and jerk.
My new favorite:
“I thought you’d be nicer since you’re not very good-looking.”
I can’t wait to use it.
“Go crawl back under your rock.”
“You little maggot.”
I like this one!
The version I have heard is: “Oh by the way, your mum called. She said to tell you that you were adopted”
I mock your value system. You also appear foolish in the eyes of others.
Past instances in which I professed to like you were fraudulent.
I engaged in intercourse with your spouse or significant other.
I’m personally for any variation on “Shut your pie hole!” Warning: when using “cake” instead of “pie,” said insult can easily become vulgar, since all those food words that start with “c” sound the same. 
a la Monty Python:
“Shut your festering gob, you tit!”
All right! My cats just got a new epithet!
A friend of mine uses “stupid cow” frequently and I find it an outstanding metaphor. Stupid cud-chewing cows…
I always liked, “I heard you. You’re just insignificant.”
I think it’s high time we revived cretin. A favorite of Uncle Cecil’s, btw.
i don’t know why but this is just funny.
My favourite, from Starcontrol 2:
Pouchless lard-log freak, and a leprous, non-functional sex organ and a wallowing, phlegm-filled Dgrunti belly-licker.
My favorite is old, but tried and true, Goober.
no one ever misunderstands
Or don’t call 'em a stupid cud-chewing cow. All you have to say is:
“Oh, just shut up and chew your cud.”
I tell my cats to shut their kibble holes all the time.
When my husband and I are play-fighting, we often refer to each other as “poo-filled.”
Some of my personal favs:
“ahh, look, here comes (some jerk), whose mother we wish had a health care plan that included abortion”
“shut your cock port”
“are we at the part where I care yet?”
“Talking to you proves that there are some things worse than death”
When I was out there in the dating jungle, I carried cards the size of business cards for when someone was annoying me.
I had four different sayings for any situation.
“I’m very sure you’re considered attractive on your home planet…”
“I do, but not with you.”
“Are you stoned or just stupid?”
“How flattering! Fuck you very much. Now, go away.”
Thinking he was getting my phone number, he’d walk away smiling. It was best if I could see his face when he actually read it.
I know, I was taking a risk, but no one was ever brave enough to come back.
“You’re not pretty enough to be a bitch.”