Quick ways to review vocab when super busy?

Hey everyone. Lately my weeks have been so hectic and I can barely find time to sit down with my flashcards. I feel like I'm forgetting everything I learned last month. How do you guys fit in quick reviews when you only have like five minutes? Maybe on the bus or waiting in line? I really want to keep my streak going but some days are just too much. Any simple routines that work for you?