as if the sun shines out (one's) backside

As though someone or oneself is better or more important than others. Various slang and vulgar synonyms for "backside" are often substituted. (Note: If one thinks this about oneself, it means that one is arrogant, conceited, or self-absorbed. If someone thinks this of another person, it means that they love or admire that person to such a degree as to be blinded to any of their potential faults.) Samantha has such an ego and acts as if the sun shines out her backside. She's absolutely head-over-heels in love with Martin. Even though I find him a bit irritating, to her it's as if the sun shines out his butt. You're not that special, you know, so quit acting as if the sun shines out your butt!