A cretin; a moron; a complete and utter idiot. Name come's from the fact that their brain is mushy like sludge. May also be because they're so thick like sludge.
Ejemplo uno:
Person A: Yo, dude, can you help me put these M and M's in alphabetical order, man?
Person B: You can't, you sludgehead.
Ejemplo dos:
Person A: Dude, I'm gonna, like, take class A drugs so I can be popular and ruin my life..but that won't matter, because I'll be popular, dude!
Person B: Urgh...what a sludgehead!
Someone or something that bites your ankles.
To a postman, an ankle biter is often known as a dog.
To an adult, an ankle biter may be a toddler.
To hikers, an ankle biter is sometimes a tick.
And so on.
When a man will search for hours to find something that is laying out in the open on a table. Items are often easily found by a women.
Man: "I have been searching for hours for keys."
Woman: "You mean the ones sitting there on the coffee table?"
Man: "Where?"
Woman: "Right there in the middle of that table."
Man: "oh, must have been Male Pattern Blindness"