A play on the term decepticon. In the prostitution industry, "transformer" means transvestite/transsexual, and "decepticon" means any very convincing transvestite/transsexual.
An "e-cepticon" is an online version, especially a female buddy or penpal whom you have known for many years, and who turns out (despite all evidence to tbe contrary) to actually be male.
HMB: I've been using this female username on this public game-related bulletin board for five years now, and people are pretty convinced I'm a woman, especially because I update the avatar occasionally with an female friend's picture. But, it's getting harder and harder to talk her into posing for avatar pics these days. I may just have to drop the whole charade and admit she was an e-cepticon.
The sexual act of talking about the video game Contra, so that the woman that you are having intercourse with will get bored and will remove your penis from her vagina before ejaculation to avoid pregnancy when you are unable to remove your penis yourself.
Bill was having sex with his girlfriend, and was about to cum. Lucky he was able to use Contra-Ception to have her pull him out because his hands were stuck.
Or
Tom had his hands handcuffed to the bed, so he Contra-Ceived his girlfriend so that he would not cause a pregnancy.