Any reson other than it looks cool

 

some wimmens like it, ehhhh, that I've heard

 

Can be a display of club affiliation, ehhhh, that I've heard

 

Are you talking about a "Getback Whip"?
http://www.chilhowee.net/whips.html

 

Yep thats it, now i know the history of them, Im not a club member other than me and my buddies going bar hopping should look good on my cross bones

 

Mine is on the left---when it was on the right it made my brake light flicker.

 

It's a giant tassel you can use to whip at cars?

 

Or as possibly for "attitude adjustment", or so I'm told. The end that attaches to the bike is of a "quick release" design...just give it a tug and you're good to go.

 

I saw a kid grab hold of one at a rally one time as people were slowly riding down the main drag. I'm pretty sure that was the last time he thought it was cool to have a long tassel hanging from his handle bars.

 

Left side. Lanyards like that are for decoration only.
Some people like fancy paint, some like chrome, some like stitched seats, some like white wall tires, some like blacked out engines, etc etc etc.
To each his own.