This is caused by, ahem, a syntax error in one of the bash completion scripts (in this case it is the completion script for
hping2). When the terminal starts a program called
bash to handle your terminal session,
bash run its initialization scripts, including the completion script
For some reason, that script on your computer is messed up (maybe somebody accidentally edited it), resulting in the syntax error. I think the right way to fix it would be to change that line to
COMPREPLY=( $( compgen -W '02 04 08 10' ) )
$ at the beginning of the line).