Buick 1993 Skylark Owner's Manual page 215

Rocking your vehicle to get it out:
First, turn your steering wheel left and right. That will
clear the area around your front wheels. Then shift back
and forth between "R" and a forward gear
,
spinning the
wheels as little as possible. Release the accelerator pedal
while you shift, and press lightly on the accelerator
pedal when the transaxle is in gear. If that doesn't get
you out after a few tries, you may need to be towed out.
If you do need to be towed out, see "Towing Your Car"
in the Index.