7. 

Overlaid Caption: Tom Rocks Maths asks Professor David J. Malan what makes him laugh 🤭

Subtitles: 

TOM: What makes you laugh? 

Apparently this question. There it is. 

DAVID: Well, I'm laughing partly because when we did a dry run earlier, you pulled that question by coincidence and I just started laughing, and here I am laughing at the fact that I was laughing last time. So I think,

TOM: Repeat jokes. 

DAVID: Yes, your choice of questions.