1. to get fucked in one sense ie, sexually.
2. when something goes wrong
1.i shag, you shag, he/she/it shags, we shag, they shag.
i like to shag. you're a good shag. i love shagging. he shagged the arse off'ae me. he shags carol.
2. oh fuck they totally shagged me over! ah shag that! shag!