"Marriage" refers to the institution of matrimony and the lifelong commitment between two people. An endless sleepover" uses metaphorical language to liken marriage to an extended and ongoing sleepover, suggesting a sense of continuous companionship and intimacy.
"With your favorite weirdo" affectionately refers to one's spouse as a beloved and unique individual with quirks or eccentricities that make them endearing.
In essence, this quote portrays marriage as a delightful and enduring partnership filled with shared moments of fun, love, and acceptance of each other's idiosyncrasies, emphasizing the value of celebrating each other's uniqueness within the relationship.