They're called "holsters". They're great. The way it works is, you put on your pants, clip the holster with the gun on, and then buckle your belt. Then you sort of go about your day, and when you go to bed, just do the "on" process in reverse.

This confers many wonderful benefits:

(1) No need to pray on whether you're going to need it! You just have the gun with you! All the time! No more having to waste time each morning asking the deity of your choice whether today is the day somebody tries to cave in your head with a brick! No more wasting money on Tarot cards!

(2) No annoying bullet holes in your thigh/butt/junk! Because your gun stays in your holster, instead of going from the floor of your truck to your holster and back again all day, you can avoid a bunch of unnecessary gun-handling, and those annoying, unsightly gunshot scars on your thighs, buttocks, and genitalia! Also protects your truck's interior and upholstery!

(3) Save money by keeping your pistol in your care, custody, and control! Did you know that by the time your replace your stolen piece-of-junk el cheapo pistol twice, you could have bought a new Glock or used Sig Sauer? As an added bonus, the crackhead that keeps stealing your gun won't know which house to burglarize, keeping the rest of your guns, plus your family, safe!

Although if you really needed a reason other than "stop shooting yourself"...