The overwhelming relaxing sensation one gets when one is completely content with their surroundings. The word derives from Calgon bubbles, as in "Calgon, take me away!" This is the feeling a person gets when they have finally been taken away and they forget their present troubles and burdens. They are "Calgonating."
"Look at him! He's so in love, he's walking on air! It looks like he could calgonate like that all day."