Green’s Dictionary of Slang

shoot! excl.1

[euph. for shit! excl.]
[late 19C+]

1. (also shoo! shoot it! shoots!) an excl. of annoyance or surprise.

2. (also shoots! shoot me!) a general excl. of intensification, affirmation.

In exclamations

shoot that hat! (also shoot that dress!)

[mid–late 19C] (US) a mild oath.