when i read the question I was lol…because I thought everyone knew what it was!! this type is called tuna baigel…because the original pp that got labeled with this term are those chassidishe spitz guys, who dress in polo shirts, kakki/denim pants, trimmed beared during the week( in short not resembling chassidishe guys) and show up at a cafe and with full heavy boro park accent say “Ich Vill a Tuna Bigel”…
I know now pp label diff type of pp with this term: working chassidishe guys or chassidishe guys who are more outside the “box”….I have not heard this term being used to describe litvish boys as one commenter suggesed.
I know pp hate labels but these kind of boys are very comfortable with the way they dress, their life style, and chassidishe background…so its not a deragetory label because they look for tuna bigel girls, they don’t want fully chassidish.