This is a link to the most popular, in my opinion/experience, "Thank You" button mod for 3.8:
https://vborg.vbsupport.ru/showthread.php?t=165673
There are 3.6 and 3.7 (and 4.0) versions as well.
However this hack, nor any that I'm aware of change reputation at all, although that sounds like a good idea- you should bring it up as a request in the mod's thread or post a request for such a mod in the request forum.
This is a mod that expands upon the rep system;
https://vborg.vbsupport.ru/showthread.php?t=201208
I suggest doing a 'search' for 'reputation' in titles only to find a number of such mods.