It's a trait that some people of Irish descent, like Watson, share.
See also: self-deprecating humor Greek, Jewish, Italian, and members of other ethnicities are sometimes known for. The difference is that Watson just didn't care to read the room before letting loose.
It is if he would describe a member of his own family this way, which I'm betting he would. He was rather famously described as a "tough Irishman" by his longtime friend, biologist Mark Ptashne.
It's a trait that some people of Irish descent, like Watson, share.
See also: self-deprecating humor Greek, Jewish, Italian, and members of other ethnicities are sometimes known for. The difference is that Watson just didn't care to read the room before letting loose.