The English jokes made by foreign friends are as follows. He said they were funny and classic, but I didn't see anything funny. Please explain what's funny!

Walking into a bar has a pun meaning, which can be "walking into a bar" or "bumping into a railing"

It's easy to think that the first sentence is the usual "two people walk into a bar", but the second sentence is "Do you think the second person will see it?" ",just know the original said is" two people hit a railing ",the second man saw the first man hit, and then hit himself. This is a joke.