noun
skin peeling off completely; skin coming off in one piece
Describes skin that has peeled or come off entirely, often in a single sheet, as from a bad sunburn or blister. Colloquial and vivid.
日焼けで背中の皮がズル剥けになった。
The skin on my back peeled off completely from the sunburn.
靴擦れでかかとの皮がズル剥けだ。
The skin on my heel came off in one piece from the shoe rubbing.
A more standard and neutral way to say 'skin peels.' ズル剥け is more colloquial and emphasizes the skin coming off in a large piece or completely.
Compound of ズル (adverb describing a smooth, sliding action) and 剥け (continuative form of 剥ける, 'to peel'). The exact origin of ズル is uncertain, but it is likely onomatopoeic or mimetic.