华语教室——歇后语1

Guess many are more interested in 歇后语 than 成语, cos 歇后语is like a quiz and u have to guess the underlying meaning. My colleagues, aft knowing wat's 脱裤子放屁（fart with ur pants down), were thrilled and was asking for more...

& so here's today's 歇后语：
杀鸡用牛刀 - Literally it means killing a chicken with a cow's knife.

Can you guess wat's the underlying meaning to this?
Answer will be out tml.... Stay tune~

p/s: Sorry Jus, still unable to find the pronunication dic for you...