There is nothing a woman loves more than finding a man who can make her laugh.
If we have to get scientific, it probably has something to do with the endorphins that are released whenever we laugh. Endorphins are chemicals that are produced by the central nervous system and the pituitary gland, causing us to feel happiness.
This chemical is released during activities like exercise, sex and of course laughter.
The more you make a woman laugh, the more she will associate you with happiness, which will make her want to be around you more - ultimately causing her to fall for you.
Just be careful not to be too hyper and overly-excited in an attempt to be funny, she will most likely find this kind of behaviour off-putting.