User blog comment:AgentGoldfish/Comic-Con Questions for Dan and Swampy/@comment-1647442-20100723193226

They won't. Think about it, if they did, it would be unrealistic. They've already done Candace's, Linda's, Doof's, and Vanessa's birthdays, and if it's all taking place in Summer, then it would be unrealistic to have too many birthdays in a 3-month period.