I'm guessing the person being the ostrich would have their head in the mud (and their ass in the air)

That's accurate, though before this thread I had never heard the sex act referred to as that...

As someone who likes to mix D/s with WAM, my WAM fantasy is to have a pale skinned submissive (with red nail polish on toe-nails & fingernails ) stripped naked and start by dunking her feet in a bowl of cold custard that has been chilled to almost freezing, then enjoy licking the custard off her feet, before getting handfuls and rubbing it on her tits to make her nipples go rock hard, and again licking it off, before making her cover herself from neck to toes in the custard before forcing her to start masturbating... but just as she's about to cum, I order her to stop and then make her give me a blow-job and swallow every drop of my cum instead and only then would I reward her with an orgasm herself... only then can she have a warm shower :devil: