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!
Kintamario!
After mario runs into an enemy
Kintamario!
After you swear you pressed jump
Kintamario!
by BFA October 15, 2004