For a large image of Patricia Quinn as the Usherette in the original 1973 Rocky Horror Show, click here.
Strictly optional. In the original Rocky Horror Show, Magenta doubled as Trixie the Usherette, who sang "Science Fiction." Trixie can wear lingerie, or an usherette costume. Women traditionally play Trixie, but there is no reason men can't. Sexy Trixies are traditional, but cheesy ones (like a big Eddie in sloppy drag) work equally well.
Trixies with an usherette costume usually carry a tray worn on a neckstrap. This can easily be made out of a cardboard box or deep box lid and a couple of belts. If you do make one out of wood, don't make it too heavy or your neck will suffer (pad the strap in back). The tray can hold candy (like gummi lips) or condoms (passed out to the audience) or cards with pictures from SFDF to hold up as they are mentioned in the song (a picture of a jar of jam; King Kong; etc. Make sure the cards are in order!). If you do throw candy, avoid hard items and avoid chocolate as it can melt and ruin people's clothes.
Trixie can also double as Betty Munroe if she wears white lingerie and has a white petticoat and veil she can put on quickly.
Some Trixies strip (check local laws to see how far is OK). Sequined pasties and pastie glue can be bought at sex shops or tacky lingerie shops. Wear pasties under your bra to surprise people who think you've taken off all you're going to. Practice stripping to the music to double-check your timing. Keep your audience in mind when you decide how much to take off. Some audiences may be offended, or overly enthusiastic.
Some Trixies wear a velvet evening gown that can be pulled off with one gesture to reveal lingerie underneath. To do this, you need a long wide rectangle of velvet and some Velcro. This look works best with long evening gloves (buy at accessory or bridal store).
Trixie's routine is up to you. Traditionally, it includes gestures which refer to the song (looking ill for "Michael Rennie was ill," pelvic thrusting when the audience yells "and fucking and sucking on," etc.). A choreographed dance is more interesting than just a straight strip, and feels less tacky.
Some casts do "Interactive Trixie" where the RHPS characters come on-stage as their name appears in the credits. Trixie interacts with them as they walk across stage. Possible ideas: Trixie scares Janet, Frank hits on Trixie, Crim flashes her, etc. This works best in theaters with experienced audiences where people know what the costumes look like, so you don't lose the dramatic effect of Frank's cape toss. Or Trixie can interact with the audience--but try to keep most of the action up front, where the majority of the audience can see without having to look backwards from their seats.
Trixie can also collect donations from the audience, or sell buttons/newsletters/etc. from her tray (as of course can the rest of the cast). Donations are easiest to collect when the people requesting them are wearing as few clothes as possible. Money can easily be collected in Columbia's hat (if it is sturdy enough--you will probably get a lot of loose change).
Trixie is a great opportunity to be creative, though there are people who get the original Usherette costume down to a "t," complete with Elvis button, "Hi, I'm Trixie" box and all. People have done everything from having costumed backup singers to wearing giant lips on their head to mouthing the song through a hole in a sheet. This is one part where you can let your imagination go wild.