Specific tastes... (Bestiality Alert)

I'll keep it simple, I kind of like the idea of a human doing a forbidden act with a creature not quite like them. I find it even more amusing when it's a male human being handled by said creature. Would be a giant dick sucking worm, a big chested bird, or just something simple. Of course we can always have a female human with a beast if that's fine, but it's mostly the same. The idea of a plot could role around a human test subject being forced to procreate or at least attempt to with some choice creatures, things will be interesting and I'm open to ideas. No worries, boundaries will be kept for convenience.