On the spur of the moment, I advised him to try it and that's what turned an innocent episode into a nightmare.

innocent 来自拉丁语 in-（表示"不"）和 nocere（"伤害"），原意是"不会造成伤害的"。引申为"无辜的、无恶意的"，在这里指"并非有意为之的、偶然发生的"。