When some players win a big derby match, they occasionally say something controversial—or they go out celebrating and do something inadvisable.
What they don't often do, however, is belt out a quick piano tune.
The win came as a big relief for the Gunners, who have had a quiet summer on the transfer front, but have now won four straight games. Meanwhile, for Spurs, defeat was followed by the disappointing news that Gareth Bale was on his way to Real Madrid.
Poland goalkeeper Szczesny pulled off a couple of big saves for Arsenal in the victory, and then took out his camera and belted out the above on the piano.
As you might know, the tune is "When the Saints Go Marching In," which is a popular song at Southampton.
Football blog Dirty Tackle speculates that the tune actually refers to Arsenal's own version of the song, in which fans sing: "We won the league at White Hart Lane."
However, as fun as Szczesny's tinkling on the ivories may have been, he should know better than many how taunting your rivals can come back to bite you.
And the league season is only three games old.