Maybe it's like goosing, but on a larger scale. Oo-er.

'Horsing' & 'Horsed' have been in common usage in the B&D world for years. So I'm told.

[TMITGS] Meaning what, exactly?

The only other usage than "horsing around" I can find on a (SafeSearch) Google, is the expression "to horse a gentlewoman", which I assume is an historical expression meaning the general assistance of a lady in enabling her to ride out. Then again, maybe I'm being naïve and it has a more Catherine the Great connotation.

I believe it involves a carpenter's sawhorse (suitably reinforced and stabilised), a willing 'victim', a quantity of rope and a good imagination. It might be a good idea to keep a chiropracter on the speed dialer too IMHO.