This isn’t as silly as it sounds. There are times when it’s the right thing to do. When a bag goes south, for whatever reason, you need to make the call of whether to repair or replace. This may help…
With synthetic bags the repair is made on the inside. Locate the problem, turn the bag inside out to fully expose the affected area. Make sure the area is completely dry. Now apply a generous coating of silicone over the area leaking. Extend the “patch” about 1 inch beyond the leak on all sides. I generally let the first coat dry and then apply another coat atop. Thoroughly dry the area. A hairdryer will speed the process. This remedy will be effective until it isn’t, but at least you’ll postpone the need to get a new bag.
With sheepskin or hide bags it’s a bit different in that the patch must be on the outside. First, 
make sure the area affected is dry. put down a thin later of silicone. Place a piece of fiberglass drywall mesh (tape) over this area and apply more silicone. After it drys, reapply the silicone. Back in the 1980’s we went through a time when sheepskin bags had thin spots with stretched, bulged, and became porous after a very short period of time. This patch worked wonders and I’ve never known the patch to fail.
I wouldn’t get carried away with this. It’s pretty tricky working within the neck of either synthetic or hide bags. You may not experience 100% success but if you can extend the life of a bag during an emergency or while waiting for a new bag to arrive, it just might be worth it.
