I feel like such a lame ass!

Today in my kickboxing class, the instructor asked me if I would help with a punch/kick combination demonstration. I thought, "Cool, I can show off what I've learned so far." So, the instructor calls out jab, jab, cross, left roundhouse, right roundhouse." Well, it turns out that he just wanted me to hold the pads while he demonstrated a jab, jab, cross. When he called out "roundhouse", my brain computed that instruction as, "he wants you to show a roundhouse kick", so I lifted up my left leg with the intention of releasing a full force roundhouse kick (for some odd reason, my left kicks are stronger than my right kicks even though I'm right-hand dominant). Instead of unleasing a powerful roundhouse kick, both of my feet slipped from underneath me and I fell flat on my ass in front of the whole class! I heard a collective gasp and saw that some people moved towards me, perhaps they thought I had gone down so hard I would need help getting up. Thankfully, the only thing that was brusied was my ego. I jumped back up as quick as I could, put my game face on, said I was o.k. and continued with the demonstration. The pathetic part of it all was that the instructor had only wanted me to hold the pads while HE demonstrated a roundhouse kick. I have a feeling this episode is going to bug me for a long time. Aaarghhhhh!! Serenity now, godamnit!