One participant attempts to envelop the other's face or chest.
Wearing a sturdy sports bra can make the "fight" more about the physical push, while being braless makes it more of a sensory/tactile experience. If you'd like to explore this further, I can help you with: Writing a scene or story featuring this dynamic.
Exploring the of "play-fighting" in relationships.
Natural changes in body composition often result in more "heft" or "weight," which participants find more satisfying for physical contact.