Squinting modifiers are those modifiers that are placed between two words so that they could be understood to modify either word.
Wrong:
The thief who was gesturing wildly stalked his victim.
Correct:
Gesturing wildly, the thief stalked his victim.
The thief, who was gesturing, stalked his victim wildly.
The thief, who was gesturing, wildly stalked his victim.
Wrong:
He said tonight he'd call me.
Correct:
Tonight, he said he'd call me.
He said he'd call me tonight.
Click on the link if you want some practice with modification.