There's a nice little enema device called the "anal spike." (Search for it on Google. It's the one that's the cleaning device, not the lube.) It's just a nozzle to stick in, with a small bulb on the end that you fill with water and squeeze.
But there are things very similar to this that are a little less embarrassing to buy that are made for sucking snot out of babies noses. They're a little smaller, but the idea is the same. You can probably pick one up at the local drugstore. Here's an example:
http://www.drugstore.com/products/pr...72&catid=26957
Just fill a glass with warm water, squeeze the bulb, and stick it in the glass to suck up water. Shove it in your ass and squeeze. You'll need to do this a few times before you start to really feel it.