his signature was just a squiggle but only he could make that squiggle.
Examples of squiggle
squiggle
The more you react to each little seismic squiggle, the less I like your chances.
From the washingtonpost.com
If I draw a squiggle on a piece of paper and present it as art, then it is so.
From the guardian.co.uk
The s-curl has become a squiggle, the eyes have once again dwindled to black dots.
From the npr.org
The other cell was thinner, squiggle-shaped, and had a large white dot in the center.
From the denverpost.com
Earlier this week, I got an e-mail in a squiggle that I could not identify.
From the sfgate.com
Unfortunately, it's not a matter of finding the single right squiggle.
From the time.com
So this squiggle is showing you the shift back and forth between ice ages and interglacials.
From the scienceblogs.com
A nicely custardy flan is touched up with a squiggle of raspberry.
From the courier-journal.com
With the exception of an upward squiggle to $500 after 87's Black Monday, gold relapsed to $400.
From the forbes.com
More examples
A short twisting line
An illegible scrawl; "his signature was just a squiggle but only he could make that squiggle"
A short twisting or wiggling line or mark; the tilde; an illegible scrawl; to wriggle or squirm; to make a squiggle; to write (something) illegibly
Surf manuever in small wave contests, also known as the butt wiggle. The squiggle is done by oscillating your board back and forth while maintaining the same forward track.