"Look me straight in the eyes" or Look at me straight in the eyes" or "Look me in the eye".
What is your context?
If you are a hypnotist and you want the person to concentrate on you maybe its OK.
"Look deep into my eyes, look me in the eyes, you are feeling tired.... look at me straight in the eyes...."
However, this expression could also be used by an angry parent who is scolding a child and wants
the child to raise his/her head and look the person in the eye while they are being lectured.
"Look me in the eye while I am talking to you".
Very difficult to do - child is scared, intimidated, (some cultures do not raise children to look
at adults in the eye - it is like staring and sometimes a sign of aggression). So! In what context
do you want to use the expression - Look me in the eye, and tell me!!!