Extreme anal play

2 cocks at once!? Lumme...!

LoveHoney sells a bunch of inflatable sex toys in varying sizes -- http://www.lovehoney.co.uk/store.cfm?tag=Inflatable%20Sex%20Toys

There are also a few reviews of them, some of which warn that you might have to reinforce the base with some tape to ensure they stay inside when they're pumped up - otherwise your toy might pop out...