Tissues and Sex

Why is it that tissues are always found after sex? For example, in Ebichu. Is it because they used it to clean up?

Personally, the wife and I just bring a small face cloth for wiping up later, and we spread a thick towel on the bed before we even start. Its that, or we get interupted later in the act and thats not cool to be scrambling for a towel when things are going good. Tissues dont do a good enough job for cleaning up, unless you use a dozen or so. Thats wastefull.