The ingenious answer to this question is found here (unfortunately only in German, but I guess there is an English version somewhere available, as the original is said to be from Ireland). If you find it somewhere, please let me know in a comment.
Thank’s to the remark by Gangstergazelle. Now the link should work!
~ PygoscelisPapua ~ 
sorry, but the link is not “clickable”.
this is a funny one! đ I enjoyed it.
Hehe, that’s what I’ve expected. All those chemistry geeks will love this one đ