[entry form 1968+, variant 1909+; by 1837 in the form ''Now you have done it'']
Idioms and Phrases with that does it
that does it
Also, that does the trick. The last requirement has been fulfilled; that accomplishes it. For example, That does it; we're ready to send in the application now, or That last screw does the trick—it's fully assembled. Grose's Dictionary of the Vulgar Tongue (1823) defines do the trick as “accomplish a robbery or other business successfully,” and presumably the it in the first term stands for the trick. [ Early 1800s ]