Best guide I've found...Note:
You can get The Party Never Stops quest via some other dialog choices so even if you screw up, keep going.
The Johnny Experience
[0:05] #1 Chapter 3 A Job Well Done (Story Related)
In Chapter 9 there are choices you can pick in order to unlock the Side Quest called The Party Never Stops as follows...
[0:30] Pick "She's a great fighter" (At the start of Chapter 9 when you first talk to Sam)
[0:59] #2 Chapter 9 To Corneo's Mansion (North of Chadley)
[2:00] Outside pick "How much?"
Inside pick "Yes"
(Chapter 9 To Corneo's Mansion - Hotel by the entrance)
[2:58] Story Choices
Sam - pick "No deal."
[3:40] Madam M - 1st pick "Poor Man's Course - 100 G" 2nd pick "It's alright."
[4:21] #3 The Party Never Stops Side Quest in Chapter 9 (Long but Easy Quest to Complete)
[5:11] Sick person location to give the medicine
The Last ones are in Chapter 14
[5:52] #4 Talk to Johnny in Chapter 14 by Area Sector 5 Undercity Station. This will start a Side Quest called Tomboy Bandit
(Kyrie is location is in the Church)
[7:21] Go to the Colosseum and complete the Special Match (Go back to Kyrie to get Johnny Wallet)
[8:12] #5 Go back and talk to Johnny. This will unlock the Trophy (Johnny's Stolen Wallet)