The couple hung out with friends and family Saturday night in Miami for a massive birthday party -- hers is July 24 and his is July 27 -- and while J Lo always has on her dancing shoes ... we don't normally see A-Rod cut loose. Dating Jennifer clearly changes a man.
Things to look for in this video:
- A-Rod & J Lo's "Sweet Caroline" singalong
- Towering double birthday cake
- Jennifer's killer see-through outfit
And don't let 'em fool you ... Jenny's still from the block, which she proved with some ass-shaking moves when the DJ put on her song, "Ain't It Funny."