Maybe the reason Im scared to do embarrissing things even when Im alone, is because I judge myself and hate myself to such an extend, that the fear of being ridiculed and shamed by an audience still exists even when Im alone, because I am that shitty audience.
Which is to say, learn to do these embarissing things as an act of self love. To show that you love yourself enough to respect it when you do silly things, even when they might be genuinely stupid because people deserve to do dumb harmless things.