What's the most annoying thing in Angband (without dying)?

[bughunter]

Townspeople.

Esp. Maggot.

"Do you mind? I'm trying to rest here until the Recall yanks in!"

(Working as intended?)

[Selkie]

For me it would have to be methodically clearing a vault and just getting ready to examine the "superb treasures" before falling through a trap door or getting teleported to another level by a hidden Q