Recently I forgot to put a belt in the jeans I wore to work, and noticed only after getting to work. It's a tight fit jeans so it doesn't really fall all the way down without a belt, but when walking with something in the pockets the jeans does get visibly down, exposing some skin.
I managed to pass the day by pulling the jeans up every few minutes and trying to walk with empty pockets, but it was still quite embarrassing and tiresome.
Are there any hacks to keep jeans from falling or getting down without a belt?
A belt is just a device to apply tension to the waist of a pair of pants. Several items can be used to gain the same benefit. Depending on your exposure to customers, coworkers and dress codes some options may not be appropriate.
Rope, the hillbilly belt. Cut a short piece of rope and use it in place of a belt
Bungee cord, Most are two short to go around a human waist, wrap it around a couple of belt loops and adjust to the correct tension.
Shoe lace or String, same principle as a Bungee cord, apply some tension between a couple of belt loops. You will probably need several wraps to get sufficient strength.
A safety pin, can be used to tighten the waistline of pants, it can be hidden on the inside, but does not do well with lots of activity (Ouch)!
How? In the restroom, you unfasten the pants and use the safety pin to put a pleat in the pants. Essentially the safety pin is a stitch that takes out how much slack you need to make up. The Pants go from ______ to _II_ with the safety pin holding the II part.
Tucking in your shirt, this will increase the friction and make your pants slide down less often. Including extra fabric like a towel around your waist (inside your pants and tucked in shirt) will also make a big difference.
An office setting offers another option, staple your pants to your shirt (in the restroom) this converts your shirt and pants into a single piece of clothing.
James already provided a few good options but one I've found (though it does nothing for appearances) is to fold over the waist band of your jeans - the waist band obviously stays the same size but you've added some material between it and your body.
As I said this does little for appearances but it has the benefit of not needing any extra items.
--Edit to elaborate on folding: Its like when you're rolling up the bottoms of your jeans. You slip your thumbs inside the waist band and turn it outwards - you may need to do this a couple of times for it to hold and the crotch will get higher up (so not something to do in skinny jeans if you're planning on having children).
I work in IT and another option that I have used on many occasions when I have left my belt at home is to use cable ties,
a couple of cable ties (known as zip-ties in some places) fastened together to extend them, then I go through 2 belt hoops and fasten them together, I tighten the cable ties where needed. Once finished, I just snip them off. I wear black pants at work so they are not really noticeable when I use them.