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.
The excited orgasm-like expression one gets upon opening a present; often used in the context of faking it.
I got the ugliest magenta sweater from my aunt, but the whole family's there at the party so I had to fake a giftgasm.