They don't hurt blondes because their so dumb. I'm surprised that I came up with this answer because I'm a blonde :p
It is just too easy to get hurt in some way. The lab is a place to be serious so do practical jokes in a place that is safe. Besides, your instructor will not be very happy if someone gets hurt and the jokester will get into trouble.
its much like what we Americans think of as trolls they are very vicious and michevious and the like to play jokes but they are very mean jokes and somebody usually gets hurt if you are in the line of fairies you are in the wrath
because you hurt so much
Because people are racist and don't like them. I believe any mean racial jokes hurt that culture.
the way u walk on it makes it hurt
You don't want to hurt the mummy's feelings
My fealings are hurt, I am crushed.
It depends if you are a guy...
Because you are unfit.
Actually, you can copyright collections of jokes. However, since people may have gotten the jokes from elsewhere, it would be hard to prove if anyone is infringing on your rights. Most who write joke books borrowed the jokes anyway. So it is hard to know where someone got a joke, especially if the wording is much different.
It hurts so much its hardly bearable.
Simply as a result of there being so many jokes made up!