This didn't come from my help desk days, but I had an IT Project Manager visit our office last year querying how she could access her emails while up here (Edinburgh v London). Our office works off thin clients, hers on desktops all on the same domain, so I suggested she locked her PC when in her office and remote in when she got here.
She arrived and I tried to get her logged in, but her PC wasn't on the Active Directory.
Me: You did lock your PC before you came up here?
Me: I can't see it on the network - did you leave it switched on?
Her: No, it's in my filing cabinet switched off but locked up...