In Urf Mode as Jhin
http://pm1.narvii.com/6034/fe276ac5441a381f65c2052ef5c7075b6f6dd8de_hq.jpg
When you only shoot 4 grenades and they all bounce 4 times, killing 4 different enemies, and those four are the same minions or champion. Not 5 or 6 but just 4.