Explanations of parodies and references in Yahari Ore no Seishun Rabukome wa Machigatteiru. / My Youth Romantic Comedy Is Wrong / My Teen Romantic Comedy: SNAFU! episodes 2, 3, 4 and 6.
Timestamps are approximate
Episode 2
0:30A Sony Computer Entertainment PlayStation Portable
4:43 “41 no ice” is a parody of “Baskin-Robbins”
8:44 Hachiman parodies the “noru shikanai kono biggu wave ni” line
Episode 3
24:09Possibly a parody of the light novel title “Boku wa Tomodachi ga Sukunai”
Episode 4
4:28Parody of Shell Brit from the anime s-CRY-ed. Also referenced Gekimetsu no Second Brit and Massatsu no Last Brit
7:33 Hikipedia is a parody of Wikipedia
9:55Pose of Giorno Giovanna from manga JoJo no Kimyou na Bouken / JoJo’s Bizarre Adventure
15:53 Reference to “kimashita waa” which is said for “yuri” or girl’s love moments, but here used for a boy’s love moment
16:19An Apple iPod Nano of some sort
18:15 “Nan… da to…!?” is a line originally from the manga Bleach
18:54 “Nazo ga subete toketa” (literally “(the) mystery is all solved”) is a line from Kindaichi Shounen no Jikenbo / The Kindaichi Case Files and the door opening is a parody of Meitantei Konan / Detective Conan / Case Closed
Episode 6
Screenshot credits: ©渡 航、小学館/やはりこの製作委員会はまちがっている。