The shortest 78 is probably this 1950's Cajun Country record. One side is a normal Cajun song or dance tune ending in the usual 'bumdiddelybumbum -- bum - bum' .
And this last 'bum - bum' - missing on the A-side - is actually 'Part 2' on the B-side.
If only I could find this record. Wasn't it by Link Davis?
Can any other 78 beat these 2 or 3 seconds?
Alex