shùn​dài

in passing

顺带 (順帶) shùn​dài
in passing adverb
to do something additionally or incidentally while performing another task

Since you're going to the print shop anyway, could you print these study materials for me while you're at it?

Frequency

Movie subtitles
2.30 per million appears in 1% of films
Written text
1.61 per million

Sources

Definitions
CC-CEDICT