It's 'oh, shit!' fast, and cut off into 'oh, sh--!' because sometimes someone you can't swear around is in your vicinity. It becomes 'ohsh', following perfectly from the beloved 'oh, shit!'

Referring to women who are sexually or romantically attracted to other women. Applies to both lesbians and bisexual women, as it is only the same-sex attraction that matters, not any other attractions the women may have.

Originates from the Greek poet Sappho, a bisexual woman from the Isle of Lesbos, from which we get the term lesbian.

A phrase used in "OH SH" situations.

May also be used when there is not enough time to pronounce the whole phrase, such as the split seconds before your head is blown off.