haha its a good idea for light weights but... i come home with my boxers covered in sweat, singlet soaked and socks wet just from lifting here even tho im in shorts n a tshirt... no chance in hell this time of the year!
buy a belt man. squatting without one is like deadlifting without chalk. you only are increasing your risk of injury, not strengthing you core.
if you want a strong core, squat deep, do heavy deads (both with a belt) then train your abs with something like standing band abs / seated wide stance hipflexor situps..
then hammer that lowerback with reverse hypers, 45degree hypers, and good mornings (both seated and standing, arched back and flat back)