snap in turtle

It's a metaphor. it's talking about sexual performance like he is unable to have an erection

There was no snap in his turtle dor two years

snapping turtle
: لاکپشت گاز گیر هست .
no snap in his turtule یعنی لاکپشتش گاز نمی گیره . استعاره از بیحال بودن - جون نداشتن