ground technique; pinning technique
In judo, wrestling, and sumo, a technique applied while both opponents are on the ground, such as a hold-down, choke, or joint lock.
underhanded dealings; dirty trick
Figurative extension from martial arts: a sneaky or behind-the-scenes maneuver, often in politics or business. Carries a negative nuance of unfairness.
政界の寝技にはうんざりだ。
I'm fed up with the underhanded dealings in politics.
あの会社は寝
He is good at ground techniques and often pins his opponent in matches.
That company apparently used dirty tricks to get the contract.
Also means a trick or secret technique, but often used in gaming or practical tips without the strong negative nuance of underhandedness.
Standard kanji spelling; used in both martial arts and figurative senses.
Rarely used kanji form; 業 can imply a crafty or underhanded technique, but 寝技 is overwhelmingly more common.
Compound of 寝 (ne, 'sleep' or 'lying down') and 技 (waza, 'technique'). Originally a martial arts term for ground techniques, later extended figuratively to sneaky tactics.