When you hold someone specials hand and you feel a jolt of electricity go through your hand, then up your arm, then through your whole body. (Like a boyfriend or a girlfriend)
Or it's a form of saying "back off bitch, he's mine" (for a girls aspect) and for a guy it would be "back off you assholes, she's mine. "
"Holding his hand was phenomenal. His warm hand when he joined my cool hand was the best thing I've ever experienced. Hand holding is the best with him."