Wiktionary
keep an eye peeled
alt. (context idiomatic English) To look out (for something) attentively. vb. (context idiomatic English) To look out (for something) attentively.
Usage examples of "keep an eye peeled".
If I was you, I'd keep an eye peeled for a wandering medicine man called Wava-something-or-other.
I think I can pry it open, if you two will keep an eye peeled for people coming down the street.
I'll be right next to you, and keep an eye peeled to see you're all right.
It would only make sense for them to want to keep an eye peeled for us to avoid surprises.