Then that's a Grapple Check, which is essentially a Melee Attack for standard PC classes. Only, you take the opposed integer of the size bonus, and double it, I believe. So, a halfgiant Fighter at level 5 with a strength of 20 would get a bonus of something like this...
+14 Grapple = 5 BAB + 5 STR + 4 Size
That's off the top of my head, though.