I hear มะเหง็ก a lot in the office, I know it's meaning is something similar to "idiot,fool" or perhaps "you are foolish", it's not negative, I've only used it and heard it used in a joking friendly manner. Not in my dictionaries though, and was wondering what you folks thought. Slang? I am in the south.

LIthobid

มะเหงก

มะเหงก [N] knuckle (of the hand)

n. the knuckle of the hand, raised as a sign of contemptor derision like nose thumbing

Def. ด้านหลังของข้อนิ้วมือที่งอเข้าด้วยกัน ใช้สำหรับเขกหรือชูให้ประกอบคำกล่าวแสดงความโกรธเป็นต้น

Cheers! I also forgot to mention that when this is said, it's usually accompanied by a "mime" of knocking on the head. Or sometimes and actual friendly hit.

Thanks for the info!

I've always seen it as a Thai version of "Would you like a knuckle sandwich?", with a bop on the head rather than to the mouth. With or without the threat actually being carried out

results from the dictionary at thai-language.com

มะเหงก the knuclke of the hand.

มะเหงกแน่ะ "(showing disbelief) (impolite)...my foot!"

แน่ะ (a particle used to emphasize how large,expansive,grand,etc. something is.)