[s9e11] Bully -

If you were referring to a different show with a "Season 9, Episode 11" titled "Bully" or featuring a major bullying plot: "Frasier" Bully for Martin (TV Episode 2001) - IMDb

: The killer humiliates his victims—former students and faculty members who failed to stop the bullying—by stripping them and dressing them in women's underwear before beating them to death. [S9E11] Bully

: The UnSub is a former high school student seeking revenge for a traumatic bullying incident from his past that led to the suicide of his best friend, Riley. If you were referring to a different show

The request most likely refers to the episode titled " Bully " (Season 9, Episode 11), which originally aired on December 11, 2013. Episode Overview which originally aired on December 11