December Birthdayers lunch together

On Christmas Eve,we had a special birthday lunch gathering for all who's born on December. I am one among the nine colleagues.It's my first time being invited and joining them.According to what they say,it's already a tradition to have all these December Birthdayers to lunch together. Well,it's a chatting time and got to know who's going before others in December days.I am the first on my 3rd day and the last one is on the 30th.