[valvar]

I have a similar anecdote which completely stunned us, but which may possibly be part of his standard routine, and thus something he does for every set of students:

He always wore the same striped sweater. At one point, he took a break to drink some water and remove his sweater. But beneath the sweater was another identical sweater!

I assume everything he did was very well-planned and part of his pedagogic system and routine, but it was often hard to tell if he was acting, or if he was actually being serious but eccentric.

[Agentlien]

I don't remember that but a lot of his antics seemed to be planned and part of his way of keeping people awake and paying attention. If it is part of his routine I wonder when he added it. I took his courses in 2006-2007.

[valvar]

I took that course in 2015 or 2016, so yeah, I guess that's about a decade in which he could have added it. I just browsed around Chalmers' course pages and am very happy to see that he's still teaching that course.