A phrase meaning we're all alone. It's meaning derives from the genus homo which only has 1 surviving species left on its branch, homo sapiens. All other species on the genus homo have gone extinct.

A male says 'no homo' before sucking another male's dick

When you want to hug someone in a non gay way

“No Homo” is an abbreviation for “No Homosexual” which is an abbreviation for “I am not going to engage in any homosexual acts with you.” and this could be said from a heterosexual or a person who identifies as gay themselves and they just don’t want to be gay with the person they are saying this to.