In Greece there are no connotations attached to two guys on a bike, except maybe that they are looking to hit on girls if they are cruising.
So Bones doesn't like it that Basil wants to ...ride behind him... and Basil doesn't get what the deal is, especially since they are being chased.
Quick color sketch I made while
and I spent some summer vacations together. Part of personal jokes between me and her as well as whacky non canon writings... and Greece.