a snake in the grass

a snake in the grass

someone who pretends to be your friend while secretly doing things to harm you It's upsetting to learn that someone you once viewed as a good colleague is in fact a snake in the grass.
See also: grass, snake
References in periodicals archive ?
It began with a snake in the grass - but ended with a snake in a substation transformer, and a power outage that affected 1,116 Eugene Water & Electric Board customers late Sunday morning.
A SNAKE in the grass became more than a phrase for one Nuneaton resident who found a slithery intruder in their back garden.