I wouldn't define this as a crack pairing at all, honestly. For me, what makes a crack pairing is not being able to come up with any in-universe connection between the characters, so you need to be on crack to justify it.. It's hard to find something like that in K-ON! although I'd admit Ritsu x Sawako would be pretty close to the line.
Geez,chill out guys! I actually don't know nor care (that much) about these canon,tease-canon,crack couple stuffs.I just wanted to made a (stupid) pun out of that igloo because it was starting to cracked. -_-