canadianspankee:
A child playing spanking with another consenting child or minor is one thing, it is entirely different in the law. I do not know about where you live but here if a parent finds someone struck their child intentionally, as like a spanking, even though the minor consented, chld welfare will investigate the adult for possible abuse and a civil suit will likely result. Once a adult has been investigated by child welfare even if one is never charged, certain jobs all of a sudden become unavailable to the adult, no company wants to take the chance. Many positions require working with children and if even a child welfare check shows anywhere on the system, actual charges or not, there is no job offer. By the way clothes make no difference if you touch the front or rear of the groin and butt area.
Based on the way that Children's Protective Services (CPS) operates where I live, if a parent were to complain about another adult engaging in any kind of consenting non-sexual physical-contact play (wrestling, football, martial arts, playful spanking, etc.) with his/her child, CPS would very likely tell that parent to keep his/her child away from that person and it might inform that person that a complaint had been made and it would be in his/her best interest to avoid contact with that child in the future. (This would be assuming no physical injury to the minor as a result of the play, of course--if there were, even though it was inadvertent, that could be grounds for a parent suing for medical costs.)
AFAIK investigations by CPS in my area aren't public knowledge unless a charge is proven, thus an innocent person who may have been investigated on a false charge (like a teacher investigated on the complaint of a student 'getting even' for a failing grade) wouldn't have that investigation showing up on a legal background check if the charge was determined to be unfounded--otherwise we'd be back to the McCarthyite concept of 'crime by accusation,' a person being effectively considered guilty merely by being accused.
Since CPS investigators certainly have some latitude in determining whether to formally investigate or not (where I live they're sometimes accused of not effectively dealing with situations wherein a child is in a dangerously abusive home environment) and in my area they complain of being understaffed and therefore overextended (budget cuts), here it would in practice almost certainly make a considerable difference (in terms of the approach taken) if a consenting child spankee were to be playfully slapped on his/her bare bottom as opposed to over his/her pants/skirt.
I'd consider it quite a different situation as well--I've occasionally given children birthday spankings (with their parents' approval), but never on their naked buttocks... --C.K.