Sleep Train became the first advertiser to drop Rush Limbaugh over his recent tasteless comments about women and contraception, but if a growing Twitter campaign to boycott his advertisers is any indication, it won't be the last.

Advertisers should know by now that Limbaugh's going to push the boundaries of appropriateness, but they're still shocked when he does so. This time, Limbaugh said he wants women to post videos of themselves having sex in return for getting their birth control covered by insurance. He told Georgetown law student Sandra Fluke: "If we are going to pay for your contraceptives, and thus pay for you to have sex, we want something for it. We want you post the videos online so we can all watch." Limbaugh made that enticing offer after calling Fluke, who was denied the chance to testify at a Congressional hearing on the contraception law last week, a "slut" and a "prostitute" who was "having so much sex she can't afford the contraception." 

Sleep Train's the only advertiser to drop Limbaugh so far, but others are already distancing themselves. Pro Flowers and eHarmony both tweeted that they were re-evaluating their ad buys, according to The Huffington Post, and organizers on Twitter are calling for a boycott of other Limbaugh advertisers, which they say include Domino's Pizza, Legal Zoom, Carbonite, and Auto Zone. 

If you're a glutton for tastelessness, you can listen to Limbaugh's latest here: