In the act of involuntary movements, usually under the influance of Meth Amphetimines. The person may be referred to as flailing (also found in the Urban Dictionary). The person may feel restless, or have aching of the muscles that cause them to move their extremities in odd ways that appear to be concidered as not normal. Movements include but are not limited to; arms, legs hands, feet, neck and head moving, dipping twisting, turning or jerking in all directions.
(verb): I don't want him to twist-a-flex in front of my parents.

(adj.): You are such a twist-a-flexer.

(noun): Hey, Twist-a-flex, can you sit still for at least five minutes?
by super_duper_gack_producer November 25, 2010
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Someone who has exceeded their limit of methaphetamines and cannot control their limbs. Past the point of spun ducky woo woo.
She called us to come help her cause her boyfriend was twist-a-flexing.
by Jonezin July 1, 2013
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