A "shameless exhibitionist" is someone who has little regard for public decency or personal privacy and seeks attention through inappropriate behavior. Synonyms for this phrase may include "attention seeker," "flaunter," or "show-off." Other possible options might include "braggart," "boaster," "blowhard," "egotist," or "narcissist." These terms all convey the idea of someone who is overly focused on themselves and their own desires, often at the expense of others. While such behavior can be amusing or entertaining in small doses, it can also be irritating or even harmful in larger amounts.