I was doing a little recon trying to figure out what's the deal with going to TJ, but was getting conflicting info. My buddy said "you have to have a passport or you can't get back in the US". Another guy I spoke with said you can just go & use your DL to get back in & others said you need 2 forms of ID. So here's the skinny, you can get in & out of Mexico with nothing more than your DL, but I would try to have at least having 2 forms of ID at least. The best recommendation is to have your passport or passport card, because it makes the whole process super fast & you get in and out much quicker & it's the correct "legal" way to do it. Now, the Mexicans will let you in, I tried going through the line where the mexican citizens go in at the border crossing, thinking they'll just let me pass by, but no, they were checking for ID & of course I didn't have my passport, so they stuck me in a little room full of horny guys like myself & their worker came in and said you need a passport but he's going to let us in this time with just a warning (he didn't take look at my DL or anything), but he did say we'll be in Mexico illegally so don't get in any trouble, so technically you could probably simply do this over and over, but if you're going to be going down there more than once in a blue moon, just bring your passport, it's much faster passing through the lines & you'll be in Mexico legally. Still regardless, avoid trouble while down there, which is easy to do, you do not want to go to a Mexican jail. So, you cross over into Mexico & right when you get out of the border station (San Ysidro), there's tons of taxi's right there waiting to take you where ever you want to go.
To sum it up:
1. get an Uber or drive and park at the border
2. walk across thru San Ysidro border crossing, make sure you have at least DL, but passport is best.
3. get a taxi on the other side (and request to go to Zona Norte...where the hoes are), don't drive yourself or you're asking for trouble
4. have fun, stay out of trouble (no fighting, no skipping out on your bill)
5. repeat the same process in reverse (step 3, 2, 1)