"Quicker than you can spit and holler ‘Howdy!’” is very fast. It’s not known if this phrase originated in Texas.


Google Books
The Old -Time Cowhand
by Ramon F. Adams
1948, 1949, 1951, 1954, 1959, 1960, and 1961
Originally published: New York: Macmillan, 1961
First Bison Book Printing: 1989
Pg. 35:
If they’d been able to understand the words, more’n likely they’d quit the bedground quicker’n you could spit and holler howdy.

16 December 1955, Atkinson (KS) Daily Globe, pg. 4:
Like Grandpa Sandy says, “Before I could spit and holler howdy, it was gone.”

Uncle John’s Bathroom Reader
Plunges Into Texas
by The Bathroom Readers’ Hysterical Society
San Diego, CA: Portable Press
2004
Pg. 157 (Cowboy Talk):
“Quicker ‘n you can spit ‘n holler ‘Howdy!’”
Very fast.