To text another persons spouse and try to have sexual relations with them. Generally when you sponaugling someone you send several thousand sexual texts to that married person. Generally one who sponagules is a douche.
To describe how amazing something can be, a word used not everyday, as to be 'Spandangaling' something has to be legendary, this can include how hilarious or memorable something will be.
David scores a goal on FIFA, on legendarydifficulty, using a goalkeeper...
David screams 'SPANDANGALING' whilst dancing in his man cave.