HELP! hole in floor
 

what's up guys it rained really hard here a few days ago and last night when I got home I saw a puddle under my rig, upon further inspection I lifted up the back seat and pulled the carpet up and there is a hole in my floor! I have no idea how the water could of gotten in. Has this happened to anybody before? if so how do I stop it from happening again and also how do I fix the hole in my floor?

Sounds to me like you may have a leak letting water in, and it's been going on so long that it rusted through the floorpan. Deteriorated door seals are a prime cause of water entry.
First you'll need to find and fix the leak before patching the hole since right now it's letting the water drain out. How much effort will be involved in fixing the hole depends on how much floor you've got left to work with. It could be as easy as a small patch pop riveted in with some caulk, or as involving as cutting out the old and welding in an entire new floorpan

Rear hatch seal. Trash in rear hatch drip channel preventing water from draining. Leaking through a screw hole in roof rack.

Find the leak with a water hose and a buddy before you try to fix the hole.

Is it right over the muffler?