The phrase "hadst a gander" is colloquial slang for taking a look or examining something closely. There are several synonyms for this phrase, such as "took a peek," "had a glance," "had a look-see," "checked out," or "had a squint." Each of these phrases conveys the same connotation as "hadst a gander," albeit with different linguistic styles and tones. The use of such slang terms in conversations adds a casual and lively element to the language, invoking a friendly and approachable atmosphere for social interactions. Overall, choosing the most suitable synonym depends on the context and the speaker's preference for language style and tone.