A knuckleheaded computer user that is often referred to in software agreements as the "end user".

The End User is often a idiot who knows nothing about computers beyond the fact that it makes porn and free music readily available.

Term of endearment for knuckleheaded children.

A party game for the very drunk and very knuckleheaded.
1. Several (3 or more) girls lie on the floor/bed naked.
2. The contestant is blindfolded.
3. The contestant then proceeds to eat out each girl's muff.
4. The aim of the game is for the contestant to correctly guess who he/she is licking out by the taste of the clam and/or the squeals of pleasure (or pain in the case of novices) of the muff owners.

that knuckleheaded dude who scrawls his name on the walls,not a graph artist.. numbskull is the true vandal.

The public flogging that takes place on C-SPAN of government officials, corporate bigshots, et al. Usually manifested in the form of relentless, fact-based interrogation by Members of Congress on unsuspecting (yet arrogant) government officials appearing before Congressional subcommittees when they try to pull a fast one by spouting fuzzy logic to defend/justify their reasoning for inane decisions that would inevitably harm American citizens and their descendants. (e.g., knuckleheaded spending programs, tax increases, etc.)

A combination of hubris and extraordinary stupidity.

— stu·bris (adjective)