Guiltmas is used to describe the guilty emotion one feels, specifically around the Christmas/holiday time, when they have failed to do enough giving, sharing joy, caroling, being nice to family & friends, and usually ruined one or more family gatherings. If you have not lived up to the holiday spirit, you definitely understand Guiltmas.
K to sister B: "Mom is still mad because Eli threw up last Christmas and ruined the entire holiday season."
B: "Well she's mad at me, too because I am already ruining Christmas 2016 just because I am getting divorced!"
Karen: "I hate the holidays. Tis the Season, Merry Fucking Guiltmas to all!"
The squeal or gasp when on the receiving end of a kick-ass gift, refers to the general excitement of unwrapping a present. Can also be faked for politeness.
Joan let out a ear-ringing giftgasm when she unwrapped her new diamond ring for her 20th anniversary.
Kyle faked a giftgasm after receiving a homemade sweater from his grandmother.