I love this thread - a big fan of gaping and anal generally
You'll make some guy (or girl) a a very lucky person!
Permanent gaping, as stated previously, doesn't really work if you want to remain continent. However, being able to gape on demand, so to speak, seems to mainly involve lots of practice and patience.
Are you into photography by any chance? If so, the gorillapod tripod things make amazing anal toys. They feel like anal beads, but you can try and cram more than one leg into your arse at a time. Or even DP yourself with the legs. They also come in different sizes from 'junior' to 'huge'... Perhaps ask for one for your birthday or something?
http://cdn.photojojo.net/store/aweso...1297539177.jpg
Failing that, I dare you to train yourself to take a butternut squash up your arse. They really do look like butt plugs!
http://www.bonappetit.com/images/tip...t_squash_v.jpg
If you like the 'toys' I'll come up with some creative dare using them