When one slaps his ejaculated penis in another's face smearing cum everywhere.
Dude, I totally gave your sister a sloppy milky slap last night.
ayon kay Ryan Huie ika-13 ng Pebrero, 2005
The act of slapping one in the mouth with a penis after the mouth has been filled with ejaculate.
Randy's leg looks like somebody just gave it a milky slap.
ayon kay Wes ika-14 ng Pebrero, 2005