I've heard of this before. It has to do with the startle reflex. I found these two pieces, although, truthfully, the second one doesn't make much sense to me.

I will look some more and get back with you,
mama

Jumping Frenchmen" is a disorder characterized by an unusually extreme startle reaction. The startle reaction is a natural response to an unexpected noise or sight. This disorder was first identified during the late nineteenth century in Maine and the Canadian province of Quebec. Lumberjacks of French Canadian descent were originally associated with this phenomenon but it has since been observed in other societies in many parts of the world as well. "Jumping Frenchmen" is suspected to be a genetic disorder and/or an extreme conditioned response to a particular situation possibly influenced by cultural factors. Symptoms tend to improve with age.
NORD


Although P50 event-related potential (ERP) suppression and acoustic startle prepulse inhibition are conceptualized as measures of sensory and sensorimotor gating, respectively, the relationship between these measures is unclear. In the present study, P50 and prepulse inhibition trials were interleaved in a single testing session to determine their relationship. Thirty-one healthy participants were presented with startle- and P50-eliciting stimuli across six trial blocks. Lead stimuli (i.e., the prepulse to the acoustic startle and the first click in the dual click ERP paradigm) resulted in significant gating, or amplitude attenuation, of responses to the startle probe and second paired click. There were no meaningful correlations between the P50 and prepulse inhibition variables, indicating that P50 suppression and acoustic startle prepulse inhibition measure distinct neural mechanisms. The implications of these findings for operationally defining the psychological construct of gating with these psychophysiological measures are discussed.

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