Of course, straight people do engage in oral sex and fingering. What they don't often do is engage in them safely, because these activities are often thought of as the prelude to "real sex" rather than as sexual acts themselves. Bad choice. Oral sex has risks for both partners, and fingering can also spread STDs. (If you never want to feel clean again, research HPV transmission by fomite. The list of pathogens that can thrive under your fingernails is disturbing.)
Anyway, I just want to say "Kudos!" to Danielle Corsetto, the author of Girls With Slingshots, who is doing a great job educating her readers about safe sex. I should head over and apologize for getting a bit lecture-y when she posted a footnote saying that STDs are now called STIs because scientists want to be P.C.*
*Oh, and all of you people who sent me the comic? I subscribe to the GWS RSS feed, so I'd already seen it... but I did appreciate the thought!