NPL (New Phrase Learned)

Today I learned from my friend Kay the phrase:

"hoisted by one's own petard"

(idiomatic) To be hurt or destroyed by one's own plot or device intended for another; to be "blown up by one's own bomb".
He has no one to blame but himself; he was hoisted by his own petard.

I love it when I learn something new without even leaving my bed.