Rule from the example.
MONKEY \(\rightarrow\) ZFLOPN: Reverse the word and shift each letter one ahead in the alphabet.
Check: \(\text{MONKEY} \xrightarrow{\text{reverse}} \text{YEKNOM} \xrightarrow{+1} \text{ZFLOPN}\).
Apply to CHARACTER.
\[
\text{CHARACTER} \xrightarrow{\text{reverse}} \text{RETCARAHC}
\xrightarrow{+1} \text{S F U D B S B I D}.
\]
Thus the code is \(\boxed{\text{SFUDBSBID}}\).