Idiom:

Practical joke ( prank )

Hit the book:

Stage fright

Phobia

Athlete

Impairment

Mime

Timid

Arthritis

Impose

The first step in mastering stage fright, and all kinds of performance anxiety, is to get a good understanding of just what kind of problem you're dealing with. There's a trick to stage fright, as there is with most phobias, and you really need to understand the trick to find the solutions you need.