“on the fiddle”别理解成“在小提琴上”，其正确的含义是用欺骗的手段（或诡计）获取利益；干骗钱的勾当；诈骗。

【例句】
My career will be over if anyone ever finds out I was on the fiddle during my time as the company treasurer.
如果有人发现我在担任公司财务主管期间用欺骗的手段获取利益，我的职业生涯就会结束。

He was accused of being on the fiddle with several others.
他被指控伙同其他人一起伪造帐目。