Red Bull works well for me.
So what happens when you are up front(single pilot) and the sun goes down and at the end of a long day your eyes start to toothpick and you realize you left your emergency Red Bull in the cooler in the Back? Do you:
a. Put the aircraft on autopilot and walk to the back to get it.(Illegal)
b. Ask one of you passengers to get it for you.(not very cool in my opinion).
c. Do a negative g pushover and a quick decell to try and get the cooler up front.(would not work if the cooler was restrained properly as per FAA regulations)
d. Push on with toothpick eyes into the inky blackness and hope you don't make any life threatening mistakes as you fly a night approach into an uncotrolled field with broken VASI lights on a non-prec runway with only MIRL.
e. De-pressurize the cabin to open the window to get some fresh air.