Seegee:
Phil, one of the actresses was Alyson Hannigan and she was involved in both spanking references, the other was Emma Caulfield who played Anya and she was there for one of the references, it was also extremely funny and the reaction of her on screen boyfriend Nicholas Brendon was perfect.
Two and a Half Men is also mentioned and I saw one of those where Charlie is in bed with an older woman, who I believe was the mother of one of Alan's girlfriends and he starts teasing Alan. She threatens to put him over her knee and he says I may just let you. Later she vows 'You are so going over my knee.' Unfortunately we never saw it.
Alyson Hannigan doesn't surprise me. She seems like she's into a certain amount of kinkiness. She does that on HIMYM too: playing sweet and innocent and then doing nasty stuff with Marshall or revealing her kinky side to her friends. I think her character might mirror her r/l to some extent. My kind of girl...
I remember that TAAHM episode, but I don't remember the actress. I did, of course, notice the spanking reference, which by no means is rare on that show. Like Alyson, I think Charlie Sheen is perfect for that role and he is definitely "adventurous" in his real life, as numerous tabloid articles (and his own admissions) will attest.