The phrase "hadst a looksee" is an informal way of saying that someone checked or examined something. If we were to replace this phrase with other synonyms, we could use words such as "glanced," "scanned," "peeked," "inspected," "surveyed," "checked out," or "perused." These words all convey the act of taking a quick or intentional look at something. While "hadst a looksee" may be a more casual way of expressing this action, using a range of synonyms can add variety and depth to our writing.