I'm in a job where I spend a lot of time in other people's conference rooms. If they're cunts I leave a couple of permanent markers in their whiteboard tray.
@fesshole you show them by [checks notes] making the cleaning staff’s life a bit harder.
@fesshole you think this makes you less of a cunt than them?
@fesshole Tip for the people who had to endure a visit from this fesser: if you have permanent marker on your whiteboard you can just go over it with a whiteboard marker and you will be able to wipe it off normally.
@jon @fesshole who's more affected : the cleaning team who probably have the right solvent on hand, or the people having a meeting who suddenly realise their passing thoughts are indelible
(I use "permanent" marker as a durable marker on my own stuff - on many surfaces it cleanly wipes off with isopropanol!)