Bongo

There is a friendly Ravager named Bongo that can appear in one of the window barriers on the map, whom you have to feed a Shiny Trinket three times, which is obtained by killing O.S.C.A.R.. Some of the locations Bongo can appear in are:

You can know for sure if Bongo is in a window barrier by looking at your mini-map and seeing a white dot in the location.

You'll know if you have found him if you hear Ravager growls, and see green glowing eyes. Once you have found Bongo, throw a Shiny Trinket at him to feed him, where you'll then need to flip round and do it two more times. After feeding Bongo three times, he will come out of his window barrier and begin fighting for you.

You can get more Shiny Trinkets from Max Ammo Power-Ups, the Picky Eater for Vulture Aid, or by killing another O.S.C.A.R..