An experimental physicist called Van Mierlo was working in the
Kamerlingh Onnes Laboratory around 1930. I believe he was
intelligent but he was somewhat dissipated and had not made much
progress in his studies. Finally, he had pulled himself together and
felt he could go to Ehrenfest for an exam. He was rather nervous
though, and although it was only 9:00 AM, he first fortified himself
with a swig of "oude klare" (Dutch gin). That was almost worse than
perfume, and after a few minutes Ehrenfest kicked him out and told
him that he could not come back until a whole year had past. The
boy was furious; he felt that this was unjust and that his knowledge
had not been tested at all. So be took his revenge. He went to the
colloquium room and there, on the sacred wall, among the names of
Einstein and Bohr and others, he wrote in bold characters his name,
underlining it with a deep gash in the plaster. When I discovered it,
I decided that Ehrenfest would be enraged by this sacrilege and I did
not want to get the poor boy into worse difficulties than he was in
anyway. So I carefully erased the name - fortunately it was written
in pencil - but I did not repair the scratch in the plaster. The young
man left Leiden and went to Amsterdam. I later heard that during
the war he was active in the Resistance and that he had been caught
and executed by the Germans. A few years ago the scratch in the
plaster could still be seen, a curious monument to a nameless fighter
in the Resistance.

H.B.G. Casimir, Haphazard Reality.

The student mentioned by Casimir was Johannes Michael van Mierlo.
Born in 1907, after his studies in Leiden he became a
physics teacher in Amsterdam. He participated in several acts 
of resistance against the German occupation in the years 1940-1943,
until he was betrayed and caught. Jan van Mierlo was executed on 
October 1, 1943 in the dunes near Overveen, together with 18 of his comrades.

Their resistance fights are described here (in Dutch):
http://www.afvn.nl/2004_4/afpag8_14.htm
http://www.afvn.nl/2006_3/afpag12_15.htm