At a recent fanmeeting event in Thailand, a lucky fan boy got to go up on stage and pose next to Nichkhun!  Once next to the handsome idol star, the fan boy saw a chance and took it.  When Nichkhun's arm went up to rest on the fan's shoulders so they could stand closely for a picture, the fan boy's arm went down . . . and his hand rested quite snugly on Nichkhun's butt.

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Nichkhun was probably taken by surprise, but he hid it really well until the picture was done and the fan boy left.  Then, he looked around, put his own hand on his butt, and showed a humorous expression of bewilderment and amusement.

Check out the humorous and cute video above.

Tip: Kathy