casual income; extraordinary revenue; incidental income; nonrecurring income; perquisite
going round in circles; game of cat and mouse; pointless and repetitive back-and-forth; itachi-gokko; Edo-period children's game in which two players alternately pinch the back of the other's hands and stack them on top of each other while saying "itachi-gokko, nezumi-gokko"
contribution (to a newspaper, magazine, etc.); submission; post (on a blog, social media, etc.)
topic; subject; much talked about; topical; in the news
offer; tender; providing; sponsoring (a TV program)