What does the tag #FollowSunday mean on Twitter?

Last tweets with this tag:

• 5 hours ago: @luisamoratori: RT @NewagersProp: @luisamoratori O bom follow vale até em #FollowSunday. Abraços
• 5 hours ago: @NewagersProp: @luisamoratori O bom follow vale até em #FollowSunday. Abraços
• 6 hours ago: @charloteyoung: I might just create #followsunday just for my use, because I cba on Fridays :')
• 2 days ago: @meytashaa: thankyou (; follow me if you wantRT @VandaLeika: #followsunday » @meytashaa « follow her now! Timeline bakalan seru dan http://mtw.tl/l1qqtx
• 2 days ago: @rootnl2k: #fs #followsunday #followsaturday #follow friday preview @michael_arndt
• 2 days ago: @YoungGregMPR: RT @YoungGregMPR: #FollowSunday ♥ @YoungGregMPR @Tormzz @iM3nd_br0knhrtz @homicidalbeauty @64_LILNATE @WifeyTypeee @Who http://mtw.tl/ljhfz8
• 2 days ago: @iM3nd_br0knHrTz: RT @YoungGregMPR: #FollowSunday ♥ @YoungGregMPR @Tormzz @iM3nd_br0knhrtz @homicidalbeauty @64_LILNATE @WifeyTypeee @Who http://mtw.tl/ljhfz8
• 2 days ago: @YoungGregMPR: RT @TeamFollowBk: #FollowSunday ♥ @YoungGregMPR @Tormzz @iM3nd_br0knhrtz @homicidalbeauty @64_LILNATE @WifeyTypeee @WhozLynxx @KamoriDaBadde
• 2 days ago: @YoungGregMPR: #FollowSunday ♥ @YoungGregMPR @Tormzz @iM3nd_br0knhrtz @homicidalbeauty @64_LILNATE @WifeyTypeee @WhozLynxx @KamoriDaBaddest @Skullzboy252
• 3 days ago: @mozart_ar: #leydetwitterk Todo buen peronista debe hacer #FollowSunday cada 4 años de familiar de NK
• 3 days ago: @frasestheoc: RT @adambrodybr: #FollowSunday: @ForeverTheOC, @OCLoko, @MischaBartonBR, @RachelBilsonBR, @FrasesTheOC
• 3 days ago: @rootnl2k: #fs #followsunday #followsaturday #follow friday preview @phila_lex @koffboy @adam_hartung @Ken718 @awesomedealsnow @TCLadyLike
• 3 days ago: @BigKFC: RT @rootnl2k: #fs #followsunday #followsaturday #follow friday preview @CoachCecily @myinstants @red_devil213 @ladybug4974 @jenport92 @goat_song
• 3 days ago: @hicks_uts: RT @TeamFranKo: ANOTHER #FollowSunday @Hicks_UTS. I don't need to explain why you should follow him. JUST DO IT! <3
• 3 days ago: @rootnl2k: #fs #followsunday #followsaturday #follow friday preview @CoachCecily @myinstants @red_devil213 @ladybug4974 @jenport92 @goat_song