It means, she is ready to fuck you if you believe her.
Used especially while you're referring to your female friend in your conversation, though it can be used by females for males. *his/her pants off* is used as an adverb in this sentence. It means, she is ready to fuck you if you believe her.
Person1: Hey mane! I heard that you were hitting on her. Is it true?
Person2: Nay, she is just trying to convince you her pants off! (convince someone your pants off)
Used to discribe someone who cant find something they just had. Usually resulting in the person turning around in circles and patting their pockets over and over.
i cant find my wallet and now ive become a circlepattern pants patter