Just in case anyone has any ideas about trying something like this you may want to read below because you can be held legally accountable:

A Korean-American woman is suing her ex-boyfriend for secretly dosing her with birth control pills.

The woman, 36, surnamed Hyo, filed a compensation suit for $5 million to her American ex-boyfriend, a neuroradiology doctor, for allegedly feeding her “Plan B One-Step” without her knowledge, according to The New York Post.

Hyo confronted her ex-boyfriend last May when she found an empty birth control pill box inside a trash bin.

“I knew you would not consent to taking birth control pills voluntarily, so I resorted to using this method,” the man allegedly confessed after admitting that he had been dissolving the pills in her juice.

The two broke up after the incident.

Plan B One Step is a birth control pill that can prevent pregnancy after unprotected sex and can be bought only with a doctor-signed prescription.  [Korea Times]

You can read more at the link.