Would shorting a pin to ground burn the Teensy?

I was wondering about what would happen if I press a button that uses internal pull-up resistors without declaring it as INPUT_PULLUP first... Thanks

EDIT: I'm talking about Teensy 3.1 mainly

Nothing would happen. Well, nothing of any consequence.

The pins on Teensy 3.1 default to a disabled state. The pin acts as if it's not even connected.

If you try to use digitalRead() without pinMode(), the pin always reads as 0 while in the disabled state. Even if you connect power to the pin, your software would always read zero.

So... I have 4 buttons. I want to put the device in some sort of sleep mode and keep only one button on to wake up. Then you're saying that to reduce power consumption I can do a digitalWrite to 0 (to disable internal pullups) on the other button pins without risking to burn anything if I press a button with pull-up resistors turned off?