For a friend. When helping to service your bike and you ask what a bolt does, and you get the answer 'FFS don't undo that'. undoing it and dumping half the brand new oil on the floor then stripping the bolt in the rush to do it back up again is not very helpful
For the Guys at Coburn and Hughes (long time ago different owners), when servicing my front brakes, please bolt them back on the bike afterwards.
And for me, when stipping an engine take the oil out before removing the starter motor, specially if you are in a shed.