1.
If you ~ your eyes or your face, you tighten your eye or face muscles, for example because you are in pain or because the light is too bright.
She had screwed up her eyes, as if she found the sunshine too bright...
Close your eyes and screw them up tight...
His face screwed up in agony.
PHRASAL VERB: V P n (not pron), V n P, V P
2.
If you ~ a piece of paper, you squeeze it tightly so that it becomes very creased and no longer flat, usually when you are throwing it away. (BRIT; in AM, use crush )
He would start writing to his family and would screw the letter up in frustration...
He screwed up his first three efforts after only a line or two.
PHRASAL VERB: V n P, V P n (not pron)
3.
To screw something up, or to ~, means to cause something to fail or be spoiled. (INFORMAL)
You can’t open the window because it screws up the air conditioning...
Get out. Haven’t you screwed things up enough already!...
Somebody had screwed up; they weren’t there.
PHRASAL VERB: V P n (not pron), V n P, V P