Will you pass a breathalyzer if an alcohol soaked tampon is inserted into your butt?

No, having a tampon inserted anally won't magically stop the breathalyzer from working.

A tampon soaked with alcohol has no place in your anus, in fact tampons shouldn't go in your anus full-stop. Obviously putting a tampon up there is a waste of a tampon and a waste of the alcohol.

No, but what you suggest would damage the delicate tissue of the anus.