Used for texting/chatting. When someone texts you something sweet, especially someone you like and you smile in public SIP. Most people just look at you like you're crazy but you keep sip-ing.
The first of a five-tiered method of quanitifying an amount of liquid beverage (often alcoholic) consumed without removing the vessel from the lips. The tiers are sip, swip, swig, swug and chug. This is the smallest of the tiers and connotes a very small amount of beverage actually consumed. Often used falesly in order to induce another person to allow you to share their beverage.