How hard do you think it is to blow a plane apart with 3.3 ounces of liquid explosives of whatever kind? I'm willing to bet quite a lot that there's no difference between 3.3 ounces and 10 gallons, when we talk about such sensitive thing as a plane. It's just a matter of know-how.

So, the question is: why? Why does it make such a difference if it's less or more then 3.3 ounces? Surprise — it doesn't. So why? My guess is, to keep security staff paying attention. If there were no quantity limit, it automatically would be off the checklist. And if there is a limit, there is also a pretty good chance that security guys checking the exact capacity of a shaving creme can might pay some attention to it's actual content. Or at least the bad guys may be afraid of them doing so...

Tricky eh?