If you're looking to secure a gas can in a truck bed, there are a few things you can do. One option is to use a bungee cord. You can loop the cord around the can and then around the side of the bed. This will hold the can in place and prevent it from moving around.
Another option is to use a ratchet strap. This is a more secure option, as it will keep the can from moving no matter how much you drive. Simply loop the strap around the can and then around the side of the bed. Then, tighten the strap until it's secure.
Finally, you can use a bed liner to secure the can. This is a good option if you're worried about the can scratching the paint on your truck bed. Simply place the can in the bed liner and it will be held in place.
No matter which option you choose, make sure that the can is secure before you hit the road. Otherwise, you could end up with a dangerous spill.