The song "Somebody's in de House wid Dinah" was evidently a minstrel show tune/skit. It appears in a banjo instructional book called "Phil Rice's Banjo Instructor", which was published in 1858. Phil Rice was a minstrel banjoist who worked the riverboat circuit and died in 1857, before the book was published.

The book has the song tune, the banjo accompaniment to go along with it, and dialogue to be spoken between verses of the song. The tune is not the same as the one I know, but it does have the same rhythm and a similar tune. The singer/speaker is suspicious that another man is in the house "making lub wid my Dinah." Since this is is an 1850's minstrel show skit, it has exaggerated dialect. Here are the three verses in the book (with some word substitution):

Oh, somebody's in de house wid Dinah,
Somebody in de house, I know,
Somebody's in de house wid Dinah,
A playin on de old Banjo.

I know dere's a fella in de house wid Dinah,
Dere's a fella in de house, I know,
If I cotch a fella in de house wid Dinah,
I'll knock him on de head wid dis Banjo.

Dere's a big ol' fella in de house wid Dinah,
Show me dat fella in de house, by Jo,
Bring me dat fella in de house wid Dinah,
I'll show him the size of my big toe.