bug-eyed 
adjective &adverb
With bulging eyes: a bug-eyed monster...
- Mars has inspired the human imagination for more than a century, generating a parade of little green men and bug-eyed monsters first sparked by the belief that the planet was criss-crossed with alien-made canals.
- Kevin isn't a bug-eyed alien, though he does a fair impression.
- Which one do you want, the spaniel with the crown or the bug-eyed chihuahua?