Resealing Alcohol Bottle Caps
Bottle caps that let you reseal plastic bottles - with alcohol inside!
These are just like the bottle caps and rings that come with a bottle before you open it. They are sealed and remain sealed until you crack them open.
you just have to take off the original cap and pry off the ring. Then pour in the new contents and put on the new cap. They make a perfect seal and the company claims they don't leak.
Obviously you'll probably want to match your liquid to the original liquid color. For instance, water bottles will work great with vodka, gin, white rum, Tequila Blanco or Everclear. Cola bottles will work good with mixers like rum and cokes, pepsi and whiskey, etc.
These are awesome for helping to smuggle alcohol onto cruise ships, into concerts or festivals, or really anywhere, like work! Ok, we kid and cannot condone drinking on the job - unless you can still do your job and/or your workplace allows it. (We used to work at a particularly lovely web design firm that would promote having a beer on Friday afternoon - but you wouldn't have to hide your drink in that case... but we digest...)
However, bear in mind with these that this sort of thing has gotten so popular that some cruise ship lines have caught onto them. Some will shake your water bottles for bubbles. In the apparent scaling up of arms in the alcohol wars, you could use something called SodaStream to inject some carbonation into your bottle before sealing.
Also, you can learn to open these without breaking the seal, thereby reusing them, which reduces the overall long-term cost quite a bit.
They'll work on 2-liter pop bottles as well - again, you just need to get close to the original color of the drink and most places won't give your bottles a second look.
All in all these little things work awesomely and it's a great way to save money by being a smuggler. Of course, your milage (and ethics) may vary