没吃过猪肉，也见过猪跑

没吃过猪肉，也见过猪跑

Literally means:

one who has not tasted pork must have seen a pig running

Actually means:

one should have some knowledge about ordinary things

It means that one should have some knowledge of something ordinary, though he may not have experienced it. It emphasizes that one should have some common sense.

有些普通的事情，虽然没有亲自做过，但是总还看见过或听说过，因此多多少少总应该知道一些。强调常识性的东西必须知道一点。