the bit where Natsu says are you here to get burned wearing the glasses is just imitating a yakuza or a gangster because he is wearing the sunglasses and the glasses symbolizes yakuza or gangsters in a way. if you search up yazuka or gangster in google images, you will find that out of the ones that wear sunglasses, they mostly wear glasses that is the same or similar (big lenses) to the glasses Natsu is wearing in the image.
for example
[![enter image description here][1]][1]
or here, an anime one
[![enter image description here][2]][2]

**EDIT:**
because the other manga was flunk punk rumble, the whole fairy tail guild (in that manga were being punks and acting tough. and yakuza was one of the typical tough guys in that sense.
please excuse my poor English but yeah, hope this helps.


  [1]: https://i.sstatic.net/hS8xN.jpg
  [2]: https://i.sstatic.net/dwBMB.jpg