Add this to your .bashrc:

clippy() { echo "I see you're trying to use the terminal …"; echo " v "; echo " ╭─╮"; echo " ⌾ ⌾"; echo " │▕│"; echo " ╰─╯"; }
function command_not_found_handle { clippy $1; }

It will result in:

$ adsf
I see you're trying to use the terminal …
v
╭─╮
⌾ ⌾
│▕│
╰─╯

Looks better in the terminal.