Shooting Gallery?

I find a shot-glass a useful adjunct when masturbating sitting at my PC. I have one that exactly fits on my penis tip when fully erect. The fit is tight enough for me to achieve the necessary sensation, by holding the glass in one hand and agitating and twisting it; thus giving me complete control of my progress whilst freeing the other hand for typing. The added benefit of course is that my ejaculation, when it arrives, is contained within the glass; thus avoiding having to clean any spill from the carpet.