Definition from Wiktionary, the free dictionary
Literally, "She/he/it is having (something) inside", the word something being implied as a penis.
- IPA: /ʃɪɡ ɑkʰvs/
- (rare) Used other than as an idiom: see შიგ, აქვს.
- (vulgar, idiomatic, offensive, pejorative) Does not have a particular meaning.
Usage notes 
The second sense is largely used in interrogative sentences, even when one wants to offend someone.