My bike keeps killing horns.

Last year for inspection, my horn chirped, but not reliably. They passed it contingent that I order a replacement. The new one came and I put it on. It makes sort of a pop noise, but no horn sound. I figured that's what a Chinese horn is worth, so I figured I'd get something better later.

So I recently bought an oem horn from a Gixxer on ebay. Hooked it up this morning. It honked great. So I swapped the mounting bracket and I tightened everything up. Then the horn honked one more time, and started the same popping noise. I measure 11v when the horn button is pressed.

How am I killing my horns?

The button completes the ground. Clean up the switch block so it makes good contact with the bar, then try it.
Steve

What's the voltage at your battery ?

Try jumping a temporary ground wire, then a battery live, to the horn terminals and see if it is a power supply problem on both or either side, I'd expect a bit of battery volt drop but 11v sounds quite a lot...points to power supply issues. Your battery voltage on a non running bike shouldn't drop too much on a 5 amp load, if you put the lights on high beam, for example.

Horns take a lot of current, they are wired through a relay on most other 12v vehicle electrics.
The switchgear contacts and handlebar wiring on these is uprated to compensate.

You can also tune the horn note, I think twin horns the notes should be a 3rd or 5th apart and sound in harmony.