Only on BBs Route, and yes ANY Route
first, trigger the scene where BB tells you about the pizza place he used to work at. this scene unlocks the possibility of clicking on an invisible object in the locker room:
click on the little "?" then talk to BB again.
next, continue the story normally until you reach the point where you have the point and click at Mad Dog. complete your tasks and trigger the last scene with BB near the road.
after this BB becomes clickable and can trigger multiple little dialogues. however, there is a secret one.
go to aisle 1 and click on the shelf with the biscuit until it says that "youll give these biscuits to BB" then talk to BB again!
How to trigger the pizza place scene ?
after the scene in the break room. go outside near the garage entrance and there should be a shiny object (BB’s key). the key can be used to open BB’s locker after clicking on it for a few time in the lockeroom. the hat should be in there!! after you click the hat go talk to him about it and you trigger the dialogue.
just look at the tumblr and you will see a pic and there is everything explained