"Bus muffin" is a term commonly used, when on publice transport, to describe someone who you quite like the look of and therefore, will do your best to sit in the seat next to them. Even if there are plenty of other seats available.
"The bus I took yesterday was full of bus muffin, man! I didn't know where to sit so I just hovered over each one until I got off or they hit me! You should have been there, man!"
"Hayley thinks Chris F. is a bus muffin. That's just not right..."