orh... easy lah... just tell him/her to close his/her eyes
because you've got a little surprise, then you:
1. ask her to open her mouth telling her you want her to taste your
fried sausage you've made today... and when she open her mouth you
quickly shove your thing in (if she's a girl lah)
2. ask him to taste the fresh oysters you've just bought from the
market today but instead you move your 'own oyster' up to his mouth
and ask him to lick, make sure you shave clean else he'll be
wondering why this oyster got hair?
good luck ya