A flexible rubber tube with an inflatable tip that is used to drain urine from the body. After the catheter is lubed up and slid up the urethra, sterile water is injected into the tip, inflating it to hold it in place.
When a foley catheter is well placed, it is normal for it to be humiliating. It is not normal for it to be uncomfortable. If, when the nurse claims the insertion is over, you feel a painful pressure in your bladder, like you have to urinate but cannot, it either means that the nurse has not inserted the catheter far enough into your body, or that the balloon tip at the end has been over-inflated. If the nurses think they can leave you with an uncomfortable catheter, lean on the call button until they come back and do it right, or give you enough drugs that it doesn't seem to matter any more.
Foley catheter placement is SOP for any hospital patient that is to undergo surgery. It is also used in the event of a bladder infection, a swollen prostate, or any other injury that disrupts normal urinary function.
Patients who are fitted with a foley catheter should drink plenty of water to maintain the flow of urine out of the body. They should also do what they can to keep the body of the catheter near the urethra clean so as to prevent urinary tract infections, which routinely develop in people connected to the device.
For me, the freakiest part of spending time in the hospital with a foley catheter was the presence of a bag of urine next to my body, connected to a tube that ran into my bladder. I was on spinal precaution, which meant that I couldn't get up or turn over by myself, and needed nurse assistance to change position. Sometimes, this meant that the nurse would have to raise the bag while moving me, and some of that urine would flow back up the tube and into my bladder. I don't know how much of a health risk that was, but I really hated that.