I have a 94 civic and when I push the brake pedal down it Its stiff like it should be but while holding it down it loses pressure like the fluid is oozing out and I was doing do about 40mph down my street and barley slowed down it scared the **** out of me haha but help is greatly appreciated thankyou

 

Check your fluid level, make sure you aren't actually losing fluid.

 

If there's no fluid loss, then the master cylinder is probably bad.

 

You need to absolutely check for fluid loss like yesterday. but if you haven't seen any in the ground where you park then like Ron@HT said bad master.