Sleeveface is the art of “one or more persons obscurings or augmenting any part of the body or bodies with record sleeve(s) causing an illusion.” You're basically posing with the record label as though it were a part of your own body.
When a incredibly annoying person sneezes very loudly and sounds extremely fake, usually to attract attention to him/herself in the hopes of a "bless you" from their peers but doesn't because everyone hates them.