Swing, like swing music I guess.
Here is an explanation about swing style playing.
Swing rhythm is based on two emphasized subdivisions of the beat which adds a horizontal feel to the music. The stress comes on the first beat and the moment the second third and the third quarter of the beat. Needless to say, this does not follow a regular, steady rhythm.
Imagine a beat subdivided into four parts: 1 e & a 2 e & a 3 e & a 4 e & a
Now add an extra emphasis right before the third quarter of the beat (the "a"): 1 e &-ly-a 2 e &-ly-a . . .