Music aids
When an individual starts to sing, hum or whistle a tune uncontrollably due to being subconsciously influenced by hearing that tune sung, hummed or whistled by another individual or having heard the tune from the t.v. or radio.
In a classroom Mary starts to hum The white stripes' "Seven Nation Army" when she has stopped Billy, who is sitting across the room, continues on the tune unaware that he has just contracted music aids.
Mary may have infected the whole class!
Mary may have infected the whole class!