mundum immundum munda: Cleanse the [whole] world, unclean

Pie pellicane, Ihesu domine,
     Me immundum munda tuo sanguine.
Cuius una stilla saluum facere,
     Totum mundum posset omni scelere.

     From the Adoro te devote (more probably the Te deuote laudo).

Piteous Pelican, Jesus Lord,
     me with your blood cleanse, unclean.
One drop of which to make whole (i.e. save)
     the whole world may be able from every crime.

Read the latter somewhat as follows:

One drop of which may be able
     the whole world to save from every crime.

Or, in a standard, and much more poetic translation,

Deign O Jesus, Pelican of heaven,
Me, a sinner, in Thy blood to lave,
To a single drop of which is given
All the world from all its sin to save.