Well, since I grossly underestimated the current draw of the horn, I thought it would be "safe" to wire it into the radio harness.

12V constant yellow Wire comes out of the radio harness - >
goes into the switch I wired -> horn -> back into the ground wire of the harness.

When I hit the horn, everything went pffft.
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The two fuses that were blown were the under hood Backup/Radio fuse and the "small lights" Fuse. Replacing the radio fuse makes the radio and the clock work again with no issues but whenever I turn on my marker lights (the first position on the light switch), the "small lights" fuse blows.

I've since disconnected the horn wires and when I get back from work tonight I plan pulling out the wires to double check that these bits aren't shorting something out.

Any suggestions would be greatly appreciated.
-g