After a friend was sexually assaulted when her drink was spiked in a bar, design student Tom Martin developed a device designed to put an end to that foul nightclub practice (see the Drink Guard, the Alcotop, and the Drink Safe Coaster for some earlier attempts at spike blockage). The Hollow is a glass with double walls, whose only way in to the liquid part of the chamber is via a special nozzle that must be affixed to the glass. Without the nozzle in place, it's almost impossible to tamper with the drink's contents — the center is hollow and bottomless, so anything pitched in in the normal manner would just fall straight through. Additionally, the Hollow sits on a special coaster that changes color as the drink sits. If not touched for over 10 minutes, the coaster is blue, signifying to the drinker the higher likelihood that the drink had been tampered with in her absence. We won't even go into how insane it is that someone had to invent this device in the first place, and just congratulate Tom Martin on being proactive about it.