How does anyone have sex with a frog?

I've seen the film 'animal farm' (not the George Orwell version) so I am fairly au fait with inter-species sex but this article in The Sun has me puzzled:

'A MAGISTRATE has narrowly avoided jail after being caught with a collection of extreme pornography — including images of women having sex with a gerbil and a FROG.

Michael Hall, 46 — who is also a school governor and worked on a council panel to protect children — downloaded the disgusting images on to his laptop computer.

When police raided his home they found 230 photos and 150 videos showing women engaging in sex acts with horses, a donkey, dogs, a gerbil, a frog and a live snake. '

The mind boggles.