A term used to mock the hairstyles of two characters from the anime Katekyo Hitman Reborn!. Mukuro Rukudo and Chrome Dukuro's hair have spikey point in the back heads, and therefore they look like pineapples. Fans of the show tend to draw and doodle Mukuro and Chrome with pineapples.
Check it out. I just drew the pineapple heads on my history homework.
Someone who is really really smart but at the same time really really dumb. They suffer from severe confusion when encountering two people with the same name. A Pineapple Head loves video games and eating pineapples. He/She is not rude, but will occasionally make a poorly timed comment. Overall good guy, just suffers from being from Hawaii.
Wow dude way to be such a pineapple head."
"Wahh I'm hungry.
Typical Pineapple Head bullshit."