Paint a naked man on a mirror with the face gone, then line it up so its your face. Practice singing to the creep version of you and pretend messing up gets you raped.
That's how I memorize things.
That's not disturbing at all
ACTION
DOHOHO DAT S0 FUNE!!!!1!!
Yeah.
This is one of my strong points; try to imagine yourself as the character, and then run thru your mind scenarios of how to do this to become better, or if it doesnt work, ask a friend to practice with you, and have you practice this on him.