"Snakes in the boots" is often used as a metaphor to describe a situation where danger or trouble is lurking. Synonyms for this phrase could include "hidden threat," "potential danger," "trouble brewing," or "unexpected peril." Other possible phrases or idioms that convey a similar sense of foreboding or danger include "tip of the iceberg," "the calm before the storm," "the sword of Damocles," or "a ticking time bomb." It's important to be mindful of these warning signs and take appropriate action before the metaphorical snakes strike.