Firehouse Subs FREE Sub with Sub Combo (Ends 12/30) December 30, 2013 by Jamie Leave a Comment Tweet . Through today – 12/30 – you can head over to Firehouse Subs and get a FREE Medium Sub when you purchase a Sub Combo! You’ll need to print this coupon HERE to get your Free Firehouse Sub. Enjoy! - Thanks, MomOnDealz!