Freeform/Pen Tool Quick Switch
If you’re using the Freeform Pen tool (Shift-P until it comes up), there are times when you may want to temporarily switch to the regular Pen tool so you can draw a straight-line segment. You can actually do this by holding the Option key (PC: Alt key) and then releasing the mouse button. This temporarily switches you to the regular Pen tool so you can draw your straight-line segment by moving the mouse. When you’re done, click-and-hold, release Option/Alt, and you’re back to the Freeform Pen tool.