KEEP ONE'S EYES OPEN (OR PEELED OR BRIT. SKINNED)
Meaning of KEEP ONE'S EYES OPEN (OR PEELED OR BRIT. SKINNED) in English
keep one's eyes open ( or peeled or Brit. skinned)
watch out for something.
→ eye
Concise Oxford English vocab.
Сжатый оксфордский словарь английского языка.
2004