What if Sportacus was having troubles with his airship and even though he has a manual he has no idea how to fix it.
Robbie, being the nosy bastard he is, sees him and comes outside and offers to help because??? He likes to build things and modify them. Especially if it could help him figure out what the airship’s deal is.
So he gets his tools and a change of clothes (like the kind a mechanic would wear) and goes to work on it and by the time he’s done he’s covered in oil, his hair is kinda messed up and he’s stripped down to only a tanktop and the top half of the jumpsuit tied around his waist.