"mother of all old jokes" joke

A new prisoner walking into prison for the first time was heading towards his cell, when someone called out' '15''. and quite a few men started laughing. The new prisoner thought to himself they aren't too smart I am older than 15, walking out on further someone called out' '24'' and place just went wild with all the guys laughing so hard.

So the prisoner walks on thinking these guys really don't know how old I am....when someone yelled out' '35'' and the place just went ballistic. Finally the prisoner made it too his cell and asked his new roomie what the calling of numbers meant.

''Well'' said the roomie' 'we have all been here so long, and have heard the same jokes so many times that we have just numbered the jokes.''

''Hmm mind if I give it a try?'' said the newbie.

Newbie steps up to the bars and yells' '27'' and it is quiet. newbie looks around and yells' '31'' and again quiet and finally he yells' '46'' and again quiet. newbie steps back and turns to his roomie and says' 'I don't understand, no one laughed at all.''

''Well kid'' said the roomie,' 'Some people can tell a joke and some can't.''