Years of commuting to work with a coffee in one hand has taught me to handle those precious cups of caffeinated liquid like a gyroscope if I want to avoid spills from sharp stops and bumped elbows. Drink holders in cars are similarly ringed with dried up coffee stains that attest to countless traffic stops... A colleague named Cameron discovered a fix to the spill-prone design of the ubiquitous Polystyrene tear tab coffee cup lids (AKA lift lock tab) while driving around the city for 1-800 Got Junk a few years back...

Now the typical coffee lid is designed so a small opening tab is ripped from edge and folded back into a pre-molded slot where it locks in place. The resulting square opening allows you to drink the coffee with the lid on, but sloshing coffee still easily spurts out. In stop and start traffic the problem is magnified because the cup opening is parallel with the direction of vehicle movement. Like a Tsunami rolling onto a shallow beach, the forces acting on the fluid are amplified, so coffee easily overflows the drink opening and spills all over the place.

Cameron's observations while driving a truck in city traffic led him to this fix: tuck the tear tab *into* the coffee cup, thus creating a fluid dampener which stops the coffee from flowing towards the opening at a perpendicular angle and sloshing out. The polystyrene tab is naturally held back against the inside of the paper cup, at about a 45 degree angle, so coffee can only enter the drink opening from the sides (parallel to the rim of the cup). The velocity of liquid in the coffee cup is thus reduced to a point where it will not slosh over during rapid acceleration/deceleration. As liquid now enters the drink area from two small openings, total flow is not significantly reduced to make drinking coffee like using a Sippy cup. Got Feedback?