I came across this joke while browsing the social medias of some piano dealers:
The picture depicts two staves: the one above with a G clef and the one below with the F clef. The time signature is 4 and 4. There is a bar line in the middle, meaning there is 2 measures. In the first measure, the treble and bass sections each have 2 whole notes/semibreves: F and B for the treble in the same octave as the middle C, and G and G for the bass section with one octave apart, in the octave below the middle C. In the second measure, both treble and bass also have 2 notes each: E and C, the octave above the middle C for the treble, and C and G for the bass, the octave below middle C. The text above the music sheet says: "My New Year's Resolution".
I'm guessing it means the musician's New Year's Resolution is to remain the same as last year, but since I'm still lacking in music theory, I'm not sure to actually understand the joke.