He gives Jack such a tired, dry look that it must seem almost uncharacteristic for Spike. He's usually the one riling people up, being inappropriate, insensitive, finding that one crack he can fit his fingernails into and then he pries and pries and pries until something breaks. For fun. For profit.
It's a great testament to just how down in the dumps he is today that he doesn't see the fun in the statement.
"What the hell possessed you to think I want to hear about your sunbathing adventures with my girlfriend? Today? "