Re: Closest I've seen...
his mouse would occasionally move erratically across the screen
A couple of roles ago we had a sister company that tended to go their own way. Amongst his other IT purchases*, without asking, the MD bought two identical wireless mice for himself and his finance guy.
He then complained of erratic mouse movements which we "must sort out". You can probably see where this is going! Their desks were effectively back-to-back, separated by a thin partition wall, and in those days wireless mice (mouses, meeses?) were single channel with no encoding so when the finance person moved his mouse there was just enough signal to cause erratic movement in the MD's mouse.
*His other one was to buy a Sony Vaio laptop from Dixons without asking. 13 months later we had to scrap it due to driver issues. Dixons weren't interested as it was out of warranty, Sony UK reckoned it was a parts bin special direct from Sony Japan so nothing to do with them,