Congress Lok Sabha leader Adhir Ranjan Chowdhury on Wednesday slammed party colleague Kapil Sibal over his Bihar poll debacle introspection remark, saying those unhappy with the party's functioning are free to leave instead of embarrassing it in public. Chowdhury stung Sibal for "giving sermons from AC rooms" and said disgruntled members may join other parties or form their own outfits.