I sing a cappella. If it's quiet, I can almost always start a song on the right note and stay in key. Conversation sets me off a bit, and guitar tuning and strumming and particularly autoharps make the tune and key disappear from my head completely. So, I sometimes talk about a song until the people quiet down and my head is clear and the melody comes back to mind.
Seems much nicer than saying, "Shut the fuck up!" and then sitting in silence until the melody comes back into my head....
-Joe-