The vanilla factorial challenge
Shakespeare Programming Language, 106 bytes
,!Ajax,!Puck,!Act I:!Scene I:![Enter Ajax and Puck]Ajax:Listen tothy!You is the factorial ofyou!Open heart

Try it online!
Uses the built-in the factorial of, which isn't described at all in the official docs.
Commented
,!Ajax,!Puck,!Act I:!Scene I:![Enter Ajax and Puck] # header
Ajax:Listen tothy!                                  # read (numeric) input
You is the factorial ofyou!                         # take factorial
Open heart                                          # numeric output