When baby powder is placed in a partner's ass crack (as if powdering a baby during diapering), and a man gets behind the 1st partner.
The 1st partner then facts onto the man's penis, covering it with a puff of powder, or a "dusting".
Iafter the cattle rustlin' we were all a bit moist sown under, so we asked our women-folk to give us all some dusty dickins.