Melt butter or margarine in blazer pan of chafing dish over direct heat; or use heavy skillet on stove.
Put in bananas.
Turn heat to medium high.
As bananas soften, sprinkle slices with a little brown sugar and a drop or two of lemon juice.
Turn once, sprinkle other side with sugar and juice and cook until soft but not mushy.
When ready to serve, turn down heat, pour in warmed rum and set alight.