Oh the good times in the Un*x lab (Mostly AIX, sigh) in my first year of Uni.

Telnet (What? SSH in 1995-6? nah) to friend's workstation

DISPLAY=0:0; export DISPLAY

xwininfo -root -all

*find some candidate window or control*

xkill -id XXXXXX

(or just fire a perl oneliner to allocate the sum of memory and swap, and then repeatedly scan it in a random pattern. But that wasn't me).*