In the screen immediately north of the town gates in QFG1 (EGA), throwing a rock at the nest is supposed to reveal a ring. However, if you're running at the time, the game freezes when your character attempts to take the ring.
Tested on Debian x86_64 with both distro package and latest nightly, EGA version of QFG1 as purchased from GOG. A savefile is attached; simply type "throw rock at nest" to exhibit the bug. Type "walk" or "sneak" beforehand to show correct behavior.