But what does it mean?

I swear I didn't Photoshop this picture in any way. I was driving home in the rain last night and found myself behind a Mercedes minivan with the vanity plate 'Warm Blood'.

I suppose it could actually stand for 'Worm Boulevard' or 'Warm/Bold', or something else I'm missing. Maybe it's just my predilection for horror films that makes me see 'Warm Blood', but seriously, what do you see when you read 'WRM BLD'?
What does it mean?