Y a pas à tortiller du cul

Literally: There's no wiggling one's backside

Example: “Les preuves sont là, y a pas à tortiller du cul : c'est lui le coupable.” — The evidence is there, no ifs, ands, or buts: he's the culprit.

English equivalent: No ifs, ands, or buts

Origin: The obvious reading is the child who squirms on the spot rather than answer the question, and the obvious reading is wrong. The 17th century had tortiller sa pensée for a mind taking the scenic route, so the way to say you were going straight at the thing was il ne faut pas tortiller sa pensée, shortened by 1756 to il ne faut pas tortiller and used in that form by Vidocq. Separately, and slightly earlier, tortiller du cul described a woman walking with a deliberate sway and a clear understanding of its effect on the audience. The two collided at the end of the 18th century into il ne faut pas tortiller du cul, meaning what the phrase means today; il ne faut pas later relaxed into y a pas à, and the whole thing is often clipped back to y a pas à tortiller. The extended version with the bottle is recorded by François Caradec in 1977. Nobody knows whether the extra clause was added to get a laugh or to cause offense, and its survival suggests it managed both.