keep your shirt on

:  to retain in one's possession or power

:  to refrain from granting, giving, or allowing

:  to have in control

:  the means or provisions by which one is kept

:  one that keeps or protects: such as

:  fortress, castle

:  of or relating to you or yourself or yourselves especially as possessor or possessors , agent or agents , or object or objects of an action

:  of or relating to one or oneself

: used with little or no meaning almost as an equivalent to the definite article the

:  a garment for the upper part of the body: such as

:  a cloth garment usually having a collar, sleeves, a front opening, and a tail long enough to be tucked inside trousers or a skirt

:  undershirt