Coke and sex go well together, but coke goggles are even worse than beer goggles, in that it will later make you think WTF...I hit that last night? Some girls like a bit of powder rubbed on their vag, but remember it's a local anesthetic so therefore reduces sensation. Also being really yaked will make a boner difficult and sealing the deal nearly impossible. And don't get stoopid, coke doesn't make you immune to STDs and babies.
I'd rather just sniff a few lines off her body though, and share some with her if she's down. It's a great, hedonistic I'm totally going to hell for this shit kinda good time :D