Setup a circle a set of chairs with one less chair then the number of people present.
Make one person “it”.
Go around the circle and have each person state which month he or she is born in. The person selected to play the “it” role calls a month and everyone with that month must switch seats. The “it” person can also call multiple months and if the “it” would like everyone to move seats then he/she calls out “Birthday Bash” and then everyone is required to switch seats.
The participant left out is the new “it”.