PFSRD:Earth Child Binder
From D&D Wiki
|This material is published under the OGL|
Earth Child Binder (Combat)
Even the greatest giants fear your technique.
Benefit: You can trip a creature of the giant subtype no matter its size. While you are using Earth Child Style, when a prone creature of the giant subtype stands up and provokes an attack of opportunity from you, if you make an unarmed strike, you can declare you are making a Stunning Fist attempt after the attack hits. You gain a +4 bonus to the DC of any Stunning Fist effect you deliver in this way.
Normal: You can only trip opponents who are one size category larger than you.