CBS has sent a memo to performers and presenters at Sunday’s Grammy gala discouraging exposed skin, especially buttocks and breasts.

Labelled “Standard And Practice Wardrobe Advisory,” the politely worded e-mail advises stars to avoid “thong-type costumes” and “sheer see-through clothing that could possibly expose female breast nipples.”

The memo continues: "Please avoid exposing bare fleshy under curves of the buttocks and buttock crack."

And also: "Please be sure the genital region is adequately covered so that there is no visible “puffy” bare skin exposure."

This for a gala ceremony that featured Pink in flesh-coloured bodysuit and upsidedown in 2010 and Jennifer Lopez in a dress whose décolletage dropped to below the navel in 2000.

The U.S. network asks performers and audience members to avoid commercial identification, obscenity or partial obscenity on their clothing. The talent is also banned from highlighting any cause that is visibly spelled out on a button.

The rules banning naughty bits are geared to prevent CBS from being hauled before the Federal Communications Commission and fined for showing inappropriate footage during primetime.

But they’re broadcasting a show featuring dozens of men and women who love to push the envelope on what is acceptable. Many, like Nicki Minaj and Lady Gaga, have made careers out of sheer fabric and exposed skin.

The Grammy Awards for the best in music are presented Sunday evening with the broadcast set for 8 p.m. ET.