>>11285446
This is a risk if you
-use chinesium equipment (not recommended for anything urethral)
-use stim equipment not intended for urethral stimulation
-use the wrong kind of lube, not enough lube or no lube

To avoid injury
-only use urethral toys and stimulators from reputable sellers (unironically check /r/sounding for good, safe gear to use)
-sterilize your stuff religiously. medical alcohol is your friend
-only use e-stim units that are meant for urethral stimulation
-don't use homemade equipment. you're not smart or diligent enough to get it right, that's the horny talking
-use sterile WATER-BASED lube, preferably something that's either recommended for urethral play specifically or at least surgilube. this is because lube needs to be sufficiently electrically conductive to avoid creating a patchy cable effect, where the lube is like an insulator, and the electrical current passes through small hotspots where the stim touches the urethral lining directly with no lube in between
-use enough lube. get some disposable syringes to use as lube applicators & get that lube in deep

Last but not least, go slow. That includes both going in and going out. Start at low power, ease it up as desired. Don't pull out when the unit is still powered on, that leaves a very small contact point (hot spot) as the surface area of the contact shrinks. And don't try to replicate things you see on /d/, that's just asking for an ER visit.