Ha, my MEPS was myself, a JAG applicant, and about 60 18 year olds going enlisted. The doctor who examined me was discussing FDR policies from personal experience, no joke. He was politically active during the 1940s.
And I shall echo the others, MEPS is a lot of hurry-up-and-wait. Please be sure you have:
1) urinated in public, if you're gun-shy
2) don't have any major problems with your leg muscles - the duck walks (ect) will weed this out
3) have printed out all your prior medical record. For me this was as easy as asking the pediatrician's office, for older folks it might be more complicated. If you think there are any issues, it might be a good idea to request all these records just to be safe. Remember, the Navy is picky about medical conditions.
4) Bring reading material. If you go to a high inflow MEPS (Fort Dix for me) there's a ton of people, and you will HURRY up to wait. Might as well have something to occupy your time.
Beyond that, MEPS isn't much more than an obscenely long physical. There's Vision, Height/Weight/Flexibility, Blood test, a piss-test, and a doctor consultation with possibility of prostate exam. (Correct me if I missed anything, this was a while ago.) All this took about 8 hours for me.