"Because the vagina doesn't have all the sensitive pleasure-receptive nerve endings the clitoris does, whatever the tongue is doing to the vaginal entrance or canal may not be all it's cracked up to be," says Sadie Allison, PhD, founder of sex toy boutique TickleKitty.com and author of Tickle His Pickle – Your Hands-on Guide to Penis Pleasing . But some people really love being tongue-penetrated. "Some people enjoy the thought of their partner tasting them, eating the body juices, or the closeness of swapping fluids," says Rosara Torrisi, PhD, an AASECT certified sex therapist and the founder of the Long Island Institute of Sex Therapy . Putting pressure on the vaginal opening can be erotic, as well. As always, the sexy-factor of tongue penetration is dependent on the preferences of the person being tongued.