Question

Snake in the Grass an unfaithful, untrustworthy, underhanded, and deceitful person; a traitor

Accepted Answer

What a snake in the grass he was! He was only pretending to be my friend. For thousands of years people have feared and hated snakes—at least since 37 b.c., when the great Roman poet Virgil used this expression. A snake is often not out in the open where you can see it; it's hiding in the grass.

Idiom	Snake in the Grass
Example	What a snake in the grass he was! He was only pretending to be my friend.
Meaning	an unfaithful, untrustworthy, underhanded, and deceitful person; a traitor
Origin	For thousands of years people have feared and hated snakes—at least since 37 b.c., when the great Roman poet Virgil used this expression. A snake is often not out in the open where you can see it; it's hiding in the grass.

Snake Grass Pretending Friend Unfaithful Untrustworthy Underhanded Deceitful