screw your face up
phrasal verbscrew your eyes/face  up 
- to pull the muscles of your eyes or face tight because the light is too strong, you are in pain, etc.(因光线太强或疼痛等)眯起眼睛,扭曲面部 - He took a sip of the medicine and screwed up his face.他喝了一小口药后做了个怪相。 
 
- He took a sip of the medicine and screwed up his face.