Noun, Suru verb, Transitive verb
skipping school or work (without a good reason); playing truant; playing hooky
「ああ・・・ちょっと、体調が優れなくて」「そうなんだ。大丈夫か?」「うふふ。実はズル休みなんです」"Ah ... I'm just not feeling so well" "Really? Are you OK?" "Heh-heh. Actually I'm playing hooky."
Also written ずる休み【ずるやすみ】、狡休み【ずるやすみ】