I've always had perfectly good results with ZIploc bags. Doug advises against them because there's all kinds of brands and some of them leak, but I've found the actual Ziploc brand doesn't leak, and I've tested them rather extensively. I use the freezer type which is made of thicker plastic than the normal type, in the 1 liter size, and they are pretty tough too. Obviously they're not as good as real bottles, but I've found they'll usually withstand a 3 foot drop to the ground without bursting, if you don't overfill them. You can fold them up pretty small, though not as small as a condom.

Thanks for the tips oh and BTW:

<<< Make sure its unlubricated as you'l kill your swimmers from the inside out LMAO. >>>

I was more concerned about destroying the ecosystem by making all the fish sterile.

RFLMAO <img src="/images/graemlins/grin.gif" alt="" /> <img src="/images/graemlins/shocked.gif" alt="" /> <img src="/images/graemlins/grin.gif" alt="" /> <img src="/images/graemlins/shocked.gif" alt="" /> <img src="/images/graemlins/grin.gif" alt="" />