I think the reason it has such negative connotations is because at a curly event one curltalker was given a tunnel cut without her permission and she was very upset; not only by the cut but by the whole experience.
She felt the owner was insensitive and making fun of her and she was very saddened by the whole thing. Michelle or Gretchen then wrote on the the thread that Jonathan felt terrible and was very sorry for offending her and giving her something that she did not consent to.
She of course still has to wait for it to grow out which we all know can take forever for hair to grow.
The purpose for a tunnel cut is to remove bulk from 3c and above hair and also some straight haired clients have asked him for the same cut. It is fairly extreme as he removes whole clumps all the way to the scalp.
I know a girl personally (teenager who hates her big hair) who was thrilled with her tunnel cut.
3B, normal porosity, med to coarse texture
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