May, in case you weren’t aware, is National Electrical Safety Month. It is also National Lyme Disease Prevention Month, National Hamburger & BBQ Month, National Home Remodeling Month, National Mental Health Month, National Salad Month, and National Military Appreciation Month.

More invitingly, perhaps, May is National Masturbation Month.

"We’re trying to encourage lots of masturbation," says Audrey McManus of Grand Opening!, a sex boutique in Brookline. "We’re trying to make it accepted as an okay thing to do."

Never mind that there are those of us for whom masturbation is a darn sight better than okay — nor, for that matter, that the National-Whatever-Month roster is already somewhat overloaded. There are apparently many Americans out there who need reminding that the occasional ménage à moi is not a bad thing. "People still have it in the back of their heads that this is something they shouldn’t be doing," McManus says. "It does leave people feeling guilty or dirty."

Well, this month, at least, we can badger the witness and butter the bagel to our heart’s content. Not only that, we can do it for a good cause. Through the weekend of May 17 through 19, Grand Opening! and a handful of likeminded organizations are sponsoring a national Masturbate-A-Thon. All you need do is pick up a pledge form, recruit a few sponsors, find a nice comfy spot, and let the charity work begin (the fruits of your labor will benefit the Federation of Feminist Women’s Health Centers).

"The sponsorships are by the minute, and you have an entire weekend to work on it," McManus says. "So I guess I’ll recommend people put a cap on [the donations]. You never know how long people can go." The real goers — those who raise the most money, that is — will be eligible for prizes from the Grand Opening! collection: porn videos, tubes of "quality" lubrication, and so on.

Unlike, say, pie-eating competitions, of course, the results of a Masturbate-A-Thon can be hard to verify. "This is totally on the honor system," McManus says. "If you come in and say you did it for 43 hours, as long as your friends pledged for that, we’ll believe you."

Local sponsors needn’t worry about going broke, however. In the four years that the annual Masturbate-A-Thon has been going, Bostonians have proven themselves to have far less endurance than their Californian counterparts — or at least less nerve. As McManus says, "People on the West Coast seem to find it easier to ask for pledges." Even McManus — more at ease than most with the topic — will be selective about whom she’ll choose as a sponsor. "I will ask my mother," she says. "But I won’t ask my dad."

On May 14, Grand Opening! will offer "Oh, Oh, Onanism," a women-only masturbation class. Masturbate-A-Thon pledge forms can be picked up at 318 Harvard Street, in Brookline, or online at www.grandopening.com. Call( 617) 731-2626 for details.