Thaw out a Cornish game hen and rinse it off. Squirt a little bit of oil into the cavity and pop it in the microwave on low for long enough to warm it up just a little (but not so much that it starts to cook). Then just lie back, spread its legs, slide your cock into the cavity and fuck. It'll be nice and warm and wet, and the bones and ridges inside will feel amazing rubbing against your shaft.
If you want a little variety, turn it around and slide your cock in through the neck hole - it's a tighter fit, but feels just as great. You can even tear a little hole in the skin and fuck the space between the skin and the meat, or slice some meat off and shove it into the cavity for a little extra pleasure. I like to go back and forth, picking up the pace gradually, until I cum hard inside it. It can get a little expensive doing this regularly, but it's the next best sensation to the real thing.