"Better late than never." isn't all that true.
When you get to class late and thus miss warm-up time everything else suffers; Lifts, WOD and mobility/stretching. Warm-ups are to get your sluggish blood moving, warm up your joints and thus the synovial fluid inside of them, muscles become more pliable, joints more flexable and you don't need to use your first few sets warming up to get to depth or get your elbows up as you would if you're cold, every rep can count if you are warm when you start. Fewer injuries, better results all from taking the time to break a light sweat before you start working.
If you do get here late while we might laugh about it 15-25 burpees is a great way to get warm in a short space of time.
5 Dead Lifts
15 Double Unders