Literally "golden eggs"
Japanese slang for testicles. Not to be confused for golden pillows which is what Son Goku called his grandfather's testicles (used as pillows) in Dragon Ball. Don't look at me that way...
It is in an insult for mario used primarily in Japan. The word "kintama" means balls. It is the joining of the two words. After scouring the web you will find an image of mario infront of the coin sprite and a strange flash animation.
After mario falls down a pit
Kintamario!
After mario runs into an enemy Kintamario!
After you swear you pressed jump
Kintamario!