Nu komt de aap uit de mouw

Literally: Now the monkey comes out of the sleeve

Example: “Hij wilde ons helpen verhuizen; nu komt de aap uit de mouw: hij wil onze bank.” — He wanted to help us move; now the truth will out: he wants our sofa.

English equivalent: The truth will out

Origin: Two explanations compete, one literal and one figurative. The literal version traces to 17th-century street and market performers, who reportedly kept a small trained monkey or hand puppet concealed in a wide sleeve, ready to be suddenly produced at just the right dramatic moment to surprise and delight onlookers — the trick's big reveal giving the phrase its modern sense of a hidden truth suddenly coming to light. The Dutch linguist F.A. Stoett proposed a different, more figurative reading instead: aap here standing not for a literal monkey but for a person's own mischievous or unreliable character (apen-aard), with houden in de mouw meaning to conceal that true nature — so the phrase would describe someone's real, often less flattering character finally coming out into the open, monkeys, sleeves, and street performers aside.