no strings attached

Etymology:

• According to one source, the origin of this phrase is from the cloth industry, where a small flaw in a fabric would be marked by a string so it could easily be spotted. This suggests a meaning of "without flaws".
• In ancient times, documents that were written on parchment had strings that were used to tie them shut, after they were rolled up. The Babylonian Talmud in Tractate Bava Metzi'a mentions an example of a man who gives his wife a get with a string attached, but holds on to the string, so that he can snatch it back. According to Jewish law, this is not a valid divorce, because the man has not properly delivered the get, by freely giving it to his wife.