This is a 10 level scale indicator of funnyness, created by professor Laughen M. I. Arsov in 2005. It goes by increasing with 0 being the lamest funny joke (probably made by your mom).

0
...
Something that is not even remolety funny (makes tumbleweed fly by). Most of the time being ignored.
Your mom's jokes. Shakespearean comedy, Oscar Wilde's quotes (well at least they almost deserve a 0), David Letterman.
1
meh
A very low, almost inexistant level of funnyness. Usually is being more stupid than funny.
Best of Your mom's jokes, Oprah's jokes, Ancient Greek comedy, Dane Cook
2
um... haha?
May seem a bit funny only in a company of complete morons (see oxymoron) or chimpanzees. Although sometimes even chimpanzees will feel ashamed.
Your mom's jokes being told by a famous comedian, George W. Bush's jokes. Lee Evans
3
heh
Jokes that may usually make people smile a little. Or a lot, when they're on pot.
Your mom's jokes heard when being on drugs.
4
hehe
Some jokes that may make you launch a little laughing sound, but usually don't create even cramps.
Your Mom jokes (not being told by your mom, actually), Russian Reversal jokes.
5
lol
Jokes that often make you feel moderately funny, you do laugh and sometimes may cramp. Most jokes fall into this category.
Any recent joke you heard from any person in the last 24 hours.
6
lmao
Jokes that might be slightly funnier that regular jokes, with cramps and, sometimes, tears. Maybe funny enough to make a little bit of pee come out, but only closer to 7 on the scale, and if you've just had a Big Gulp.
Your Mom jokes about your mom's jokes being told by a famous comedian.
7,
rofl
Some jokes that make you cramp, often cry and your face turns red. Uncontrolled emotions and sudden breaks of laughter are possible.
Watching The Simpsons.
8
roflmao
These jokes make you shit blood and may be considered as lethal to Your Mom.
Watching The Simpsons on drugs.
9
XD
put to a 10-year treatment against such things as schizophrenia and personality split.
Watching your mom watch The Simpsons.
10
a splode
WARNING!! Even hearing these jokes in distance can make your head asplode. Not recommended for mixing with reading this article.
Uncyclopedia, George Carlin and monty python

jj