Did you ever hear the joke that goes: Helen Keller walked into a bar, and then a chair, and then a table.
She had a disability. That's not funny.
I've seen Helen Keller and she was very capable compared to other blind people, so if it wasn't for Isaac newton she would have bumped into a lot more things.
Making fun of blind people isn't funny at all. Its not something you should be making light of and they have real struggles that really make their lives hard without you joking about it.
Life's hard without you worrying about it.
Life's hard for blind people, too, and they don't need to hear you making fun of them, do they? People will believe that you're being very rude and callous if you tell jokes like that.