Peppermint Hippo Lost & Found | Side quests South Park: The Fractured But Whole Guide

Jimbo (from Jimbo's Guns) will ask you to find his wallet, which he left at Peppermint Hippo. You can go there after completing The Bowels of the Beast. The wallet is on one of the tables in the main part of the club.

After you return the wallet to its rightful owner, you receive a new Summon. Unfortunately, the number of times you can use it is limited, so it is worth leaving it for more difficult battles. The item you need to use to summon Jimbo and Ned is a radio - then you select an extensive grid on the arena, on which they perform a powerful attack (able to deal damage taking 1 of opponents' health).