I asked fellow teachers what they think about while invigilating examinations.
(It's exam season, and the UK has placed an embargo on current teachers invigilating, so it's a passing luxury / burden.)
Work.
Marking.
Summer holidays.
A stiff gin and tonic.
Sex.

Sex - ?

I used to try to get assigned to exams late in the season, so I could stroll up and down trying to read the graffitti left by the bored and desperate. Until the students cottoned on to what I was doing.

One time I tried gingerly leaning against the edge of a particularly full of graffitti desk, to rest my weary feet (you can't sit or stand still in invigilation, it's against the rules, so trainers are a must to pace up and down), and the entire thing smashed into tiny pieces beneath my weight, leaving me flat on my bum in the centre of the exam hall, and the examinations officer rolling his eyes heavenwards as he realised he had to enter the incident in the official record.