人来疯 - Chinese Idiom

人来疯

Literally means:

people come crazy

Actually means:

show off one's liveliness in the presence of visitors

It originally means a child who behaves normally at usual times acts in a spoiled way or becomes mischievous when guests come to visit. In general, it means one becomes extremely excited in the presence of visitors. It may also refer to such a person. Derogatory.

原指小孩子平时很正常，但家里来客人的时候，就撒娇或胡闹起来。泛指来了客人，精神异常兴奋。也指来了客人就精神兴奋的人。具有贬义色彩。