Append query string via URL rewrite in apache

Hi,
Googled around but I couldn't find anything similar. I'm looking to do the following in apache..

if a user comes into the following URL.

http://www.example.com/some/thing.cid?wholebunch_of_stuff_here

keep the URL exactly as is BUT add &something at the very end of it.

thanks in advance

What mod_rewrite rules have you tried?

Please post what you have tried to do first.

Did you try something like:

RewriteRule ^some/thing.cid.*   /some/thing.cid&something [QSA,L]