An alternative form of the common term "tl;dr".
Is used to mean "too long; didn't listen".

Other forms of the "tl;d_" include tl;dr (too long; didn't read) and tl;dw (too long; didn't watch).

"tl;dl" is usually used when a song is uninteresting, boring as fuck (see also: Panic! at the Disco), and like an hour long.