To lightly tap or poke with your finger someone for fun while adding the sound effect. It can be used with objects too.
Person 1: "Hey, can you hand me that broom, right there?"
Person 2: "Yoink! I just yoinked you with a broom handle!"
Person 1: "I am soo going to get you back someday."
Is not done in a sexual way but in a way to prank a homie
Shane: "Im gonna yoink you into another dimension"
Matt: "No pls"
also can be used to exclaim after yoinking someone
*Shane Yoinks Matt
Shane: "YOINK!"