look sideways at
Glance at suspiciously or amorously, as in I'm sure the detective was looking sideways at me, and it made me very nervous, or They were looking sideways at each other, and I don't think it was innocent. [Mid-1800s] Also see look askance.
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.