It was his air of seriousness, almost of pathos, that made it so irresistibly amusing.
We said we yearned to hear it, that we wanted a good laugh; and they went downstairs, and fetched Herr Slossenn Boschen.
He appeared to be quite pleased to sing it, for he came up at once, and sat down to the piano without another word.
"Oh, it will amuse you.

You will laugh," whispered the two young men, as they passed through the room, and took up an unobtrusive position behind the Professor's back.
Herr Slossenn Boschen accompanied himself.

The prelude did not suggest a comic song exactly.

It was a weird, soulful air.

It quite made one's flesh creep; but we murmured to one another that it was the German method, and prepared to enjoy it.
I don't understand German myself.