I accidentally rang the crew call button while using the lav from CPT to LHR last night. I must have been completely off, because I had no idea why people kept knocking frantically and asking if hadn't died or something of the sort. Finally after three knocks, I started shouting (well, raised my voice over the engines) through the doors that I was fine, and why are you bothering me while I conduct my business, leave me alone, this is not economy so there is no queue etc. etc...

Finally realized the crew button was on Felt a little embarressed when I emerged; got some odd looks from the crew.