Dear Go-To Girl,
I'm a guy interested in being pegged and am finally involved with a woman interested in pegging me silly. While I suppose the dildo through the Y fronts trick would work, I'd love to surprise her with a harness as a gift. While I'd like it to be fairly inexpensive, my main dilemma is that with my lack of female genitalia, I'm really lost as to what would be comfortable for her to wear; thong style, two strap... help!
GTG note: For the uninitiated readers among you, "pegged" means "guy getting fucked in the ass by a girl wearing a strap-on."
I'm warning you: don't go from zero to dildo in one night. If you haven't already, start out with fingers and I highly recommend getting a butt plug (see link below). You need to be able to get 3 of someone's fingers (yours or hers) in your ass before you unpack your strap-on.
This is not 1966, and you are not butch lesbians, so don't bother with the dildo-through-the-tighty-whities trick. It's completely obsolete and the damn thing needs to be, like a real live penis, securely attached to the person who's fucking you with it.
So begins the actual answer to your question, which is: what kind of harness should I buy my gal? I would suggest you consider two things. First, does she like to wear thongs a lot? If not, she probably won't like a thong harness. I've never used one, but I don't think I would like it. A two-strap keeps the straps and whatnot out of the gal's "area" and I imagine a thong-style wouldn't do that. So I say two-strap. Secondly, while you should consider cost, a leather harness is a worthwhile investment if you hope to get pegged with any regularity. I have a nylon harness that cost about $50 and I fucking hate it. The straps chafe my skin and it just feels cheap. The Terra Firma harness (see link below) is a good intro-level leather harness and, I can assure you, it stays put and doesn't chafe.
The dildo you choose for anal should be relatively flexible so it molds with your (or her) body (see link below). And, obviously, get silicone so you can boil it after you're done.
Lastly, and most importantly, DO NOT forget lube. The only lube I use for anal is called Maximus, which is nice and thick and lasts a long time (see link below).
Ryder Butt Plug: http://www.babeland.com/page/TIB/PROD/butt-plugs/TG348115
Terra Firma: http://www.babeland.com/page/TIB/PROD/harnesses-2-strap/RW490181
Siren 4 Silicone dildo: http://www.babeland.com/page/TIB/PROD/dildos-silicone/LN330333
Maximus lube: http://www.babeland.com/page/TIB/PROD/safe-sex-lubes/FC825080