S.W.A.K.
sealed with a kiss (written at the end of a love letter or on the back of its envelope).
Also SWAK [swak] /swæk/.
Origin of S.W.A.K.
First recorded in 1925–30
Dictionary.com Unabridged
Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
Examples from the Web for swak
“SWAK” is where we see that Tony is more than a wise ass in a suit.
NCIS’s 11th Anniversary: Michael Weatherly’s Top 10 Moments|Michael Weatherly|September 23, 2013|DAILY BEAST“SWAK,” or sealed with a kiss, is the virus episode where I get the plague.
NCIS’s 11th Anniversary: Michael Weatherly’s Top 10 Moments|Michael Weatherly|September 23, 2013|DAILY BEAST