Squirm : v. tr. Twist in several turns (a flexible thing), in particular by nervousness.
To eat ; eat fast. How you squirm!
Pass away. Limp.
Related article: Twisting.
The expression "You don't have to wiggle your ass (to shit straight in a bottle)": We can no longer hesitate, we have to decide, we have to make a decision. It's undeniable.
It was in the XNUMXth century that we find the expression twist his mind to designate complicated paths of thought.
In contrast, one could say, don't twist your mind, quickly shortened to a you don't have to squirm, expression attested in 1756.
but before the end of the XNUMXth century, there was already a twisting of the ass applied to women who walk while swaying their hips.
The combination of the two expressions at the end of the XNUMXth century gave you don't have to wiggle your ass with the same meaning as this expression. Over time, the set has been shortened to there is no squirming.
As for the extended version which does not always contain in a bottle, it was created in 1977 by the French writer, biographer and author of pastiches François Caradec (1924-2008) in his Dictionary of popular and slang French.