Having a bad day, just want to end it? Give this a try!

File / New / PCB
Place a few tracks. Select some and set Solder Mask Expansion Mode: From Rule.
Go to Design Rules, add new Solder Mask Expansion rule. Custom query: "IsTrack AND SolderMaskExpansion". Set expansion to a negative value.
Hit OK.
You have now set the bomb. To detonate it, select an affected trace. It will attempt to refresh the trace's properties, and fail for some reason. Enjoy your hard crash.

(Seems to work in AD16.0, anyway.)
Workaround: use query "IsTrack AND (SolderMaskExpansionMode = 'From Rule')" instead.
Tim