to press together and move with a rotating or back-and-forth motion
In this day and age, i seriously think that if a woman asked me back for coffee then 9 times out of 10, i would presume that coffee beans would not be the only things that would be grinded. Or- She grinded her hips against my....
To dance dirty with a girl or a boy, at a party for example.
"hey joe, did you go to that party last night?"
"yeah dude! I grinded with Jane!"
came about through playing too much of the Tony Hawk's Pro Skater games (that's a skateboarding video game ladies and gents) and realising that "I did a grind" was too awkward to say.
I grinded that rail then did a kickflip onto the tabletop