Blackmailing, but using your vagina as the weapon of coercion. Generally not a good idea, as it assigns your vagina a material value and is basically prostitution. Not that there's anything wrong with prostitution, but you should know that that's what it is.
Tamalia: "Hey baby, I want you to come hang out with me and my girlfriends on Sunday! We're going shoe shopping and they really want to meet you!"
Mark: "Aw, I can't sweety baby pie - I promised my mom three weeks ago that I'd come over and fix her sink that day."
T: "If you don't come, you can bet you're not getting laid for a week!"
M: "...are you seriously vagmailing me right now? Wow."