Posting up (sitting up and taking both hands off of the handlebars) like an asshole at the end of a cycling race or a group ride when you won the sprint in for 16th...or anything but for the win.
The Cat 5 Salute (Category 5 is for beginners) demonstrates you are a complete noob at riding/racing your bike.
Often times accompanied by losing control and crashing.
"Did you see that guy do the Cat 5 Salute at the end of the group ride?" "I don't see a guy...oh wait, did he hit that speed bump and crash over that guardrail?" "Yup..."
Surprise, nocturnal cat attacks in which they fly silently through the air from unknown locations and altitudes before pouncing with full force anywhere on your bed at night.
Jim: "Thanks for letting me spend the night Sally, I always knew this day would come. Your cat is sooo cute! Does he always sleep all day? Sally? Where are you?
Sally: Yes, yes he does Jim. I'm under these six quilts and if you know what's good for you, you'd better do the same.
Jim: Are you kidding me? It's the middle of summer!
Sally: No, no I'm not kidding Jim. I'm sorry to say I have a really bad problem with cat-bombs and most men only stay over once after seeing their faces in the morning.