  On 13-01-2024 the annual wintersymposium of the Koninlijk Wiskundig
Genootschap (KWG) was held in the academiegebouw in Utrecht. The symposium had
the theme ``inzichtelijk abstract''. Thomas Rot gave a lecture on his favourite
theorem from topology. This article is a written account of this lecture.
Audience comprised mostly of high school teachers and that is also the target
audience of this article. The slides (in Dutch), which contain more pictures,
are available~[8].
