A snough (pronounced snoff) is a combination of a sneeze and a cough which happen at the same time. In this case, one doesn't know whether to say 'bless you' or just ignore the noise!
If someone catches you making an embarrassing noise, spoughing is saying something loud/coughing/laughing in hopes that it will retroactively cover up the embarrassing noise.
Noise coming from A: brrrrzzz
B walks in.
A: *cough, cough*, I must be getting a cold.
B: Are you spoughing?