Size zero actress Kareena Kapoor will not be able to celebrate her birthday with boyfriend Saif Ali Khan. Instead the actress will be shooting for Raj Kumar Hirani’s 3 Idiots.The actress who brings in her 28th birthday on September 21, will be in Ladakh, shooting for the film with actor Aamir Khan. She will definitely not have time to fly down to Mumbai and attend a birthday bash, as is being speculated by some.