Style: how about the following?

```ruby
def find_or_create_user
  User.find_by_yammer_user_id(invitee_id) || create_user_from(invitee_id)
end

def create_user_from(invitee_id)
  user = User.new
  invitee_data = @event.owner.yammer_client.get("/users/#{invitee_id}")
  YammerUserResponseTranslator.
    new(invitee_data, user).
    translate.
    save!
end
```