The speaker was talking about someone who needed to be careful. This is a mashup of “walking on thin ice” (to proceed with caution or great care) and I think “in deep water” (an overwheming situation) because of the context. However, “walk on water” (do something extraordinary or impossible) certainly should not be ruled out, as it is scrambled in the malaphor. A shout out to David Stephens who heard this one. David said that he recently slipped on a wet floor and broke his toe so this malaphor really resonated with him.
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