The Squinting and Crooked strikes server the same purpose: they are defensive cuts that are immediately turned into attacks.
Here are the definitions and images according to Meyer followed by images from other masters:
Krumphauw – Crooked Cut
This cut is executed thus: stand in the Wrath Guard with your left foot forward; if your opponent cuts at you, then step with your right foot well out from his stroke toward his left side; cut with the long edge and crossed hands against his cut, or across on his hands between his head and blade, and let the blade shoot well over his arm, as can be seen in Image D in the figures on the upper right.
Talhoffer: Fencer on the left is mid-way through performing the crooked strike
Talhoffer: Fencer on the right completes the crooked strike by striking the head
Paulus Hector Mair
Sequence by Bill Grandy
The crooked strike can be performed against the strong of the blade or the arms. Either way, a wide step is necessary to execute this safely.
The timing isn’t exactly easy, this action cannot be started until the opponent is committed to his attack.
This cannot be used against the weak of the blade. If you try they can easily slip the tip or otherwise react.