In this version the right hand plays all the notes exactly as Chopin has written them, while the left hand plays Chopin’s patterns, but in an entirely different key—B major, the “relative major” of Chopin’s G-sharp minor. It sounds preposterous, shocking, and hopefully amusing to anyone who knows the piece, but perfectly normal to anyone else (which is part of the joke).
Though this is not intended as a serious piece, it happens to illustrate a basic fact of music theory: a “third” is just two notes, not a complete three-note chord (triad). These two notes can belong to either of two very different triads, one major and one minor. Composers have often used this ambiguity in their compositions. In this etude, all of Chopin’s right hand notes are thirds, so they can be interpreted differently—in a major key, rather than Chopin’s minor.