perl -e'print"*shun*
"for 1..50'

Or using Scott's trick:

perl -e'print"*shun*
"x50'

(Both assume a Unix-like shell.)

Cheers,
Ben

PS Ruby still wins at 25:

ruby -e'puts"*shun*
"*50'

PPS OK, there is a shorter entry, but it didn't include invoking the language etc. The Ruby program proper is 16 chars.