Southwest Airlines is celebrating Facebook like No. 3 million with a promotion for its fans on the social network.

Travelers booking flights on Southwest.com can enter the promo code “LUV2LIKE” to receive 50 percent off round-trip “Wanna Get Away” fares for the following seven dates:

  • Sept. 5
  • Sept. 11
  • Sept. 18
  • Sept. 25
  • Oct. 2
  • Oct. 31
  • Nov. 6

Book quickly: The promotion expires at 11:59 PT Friday.

Readers: What other ways have you seen brands celebrate milestones on Facebook?