a white person who is only thought of as attractive by black people

Used to describe (generally female) imagery that's suggestive, but in a PG-13 sense rather than an R or above sense.

A blackmagnet is a white girl who can only seem to attract black men as sexual partners. Some are discontent with this attribute of themselves, but most thrive in their new inter-racial lifestyle. Regardless of the victim's stance, it is common knowledge that once one goes black, there in no going back.