My favorite insults are the ones that don't rely on curse words - they're more creative - but every now and then a good curse word can have the desired effect. This site has them listed by movie, or you can watch it below.
A favorite of mine from childhood:
"I'll use small words so you'll be sure to understand, you warthog-faced buffoon."
And a few others I liked:
"You despise me don't you?" Responded offhandedly with: "Well, if I gave you any thought, I probably would."
"You are a smelly pirate hooker."
"You're a cantaloupe."
"There's a name for you ladies, but it isn't used in high society... outside of a kennel."
"I'd go with you..." Cut-off by, "I know, there's a problem with your face."