fanservice

(fandom slang) Elements added to a television program or similar entertainment that appeal to avid fans but are of little interest to outsiders.

(fandom slang, chiefly ACG, often derogatory) The inclusion in a work of fiction of material, especially of a racy or sexual nature, which may or may not have relevance to the storyline and is designed merely to excite the viewer.

(fandom slang, idol fandom) Special interactions from idols to their fans.