After seeing people coming and going from the neighbor's house, I began to suspect there was some funny business taking place, 看到我邻居家老是有人进进出处,我开始怀疑他们在进行什么非法交易。
例句-1:The cop knew the crook was armed and dangerous. When she finally caught him, he was told to throw down his gun and put his hands up over his head. She also warned him not to try any funny business. It was clear that she wouldn't hesitate to shoot if he made any wrong moves.
例句-2:Recently, Paula's husband was busier than ever, and had to go out of town one weekend every month to meet with clients. She started to wonder if there was some funny business going on. Soon enough, she found purchases of women's jewelry and lingerie on his credit card bill. He was having an affair with his secretary!