Parents are Gross Griffin and Quagmire

Together:
You never should look at your mother's boobies
No matter how big and round they are
You'll end up seeing something you don't wanna
It's guaranteed to leave a mental scar
You never should look at your daddy's penis
When he's walkin' down the hall on Sunday morn
An acorn in a nest of twigs
And underneath two fetal pigs
It'll make you wish you weren't even born
Parents are gross, parents are gross...

Quagmire:
Parents are gross, parents are gross...