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A gym shirt with the sleeves cut-off creating large arm holes often encompassing much of the side down to the abdomen. In many cases, this includes exposing the nipple. Worn by tough men lifting weights.
Man, this casey shirt is awesome. It really lets my pecs breathe.

I can't believe they wore their casey shirts to the meeting. How unprofessional.
by the_office_oracle April 16, 2009
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