The pop stars have taken a liking to inkings since shooting to fame, especially Harry Styles and Zayn Malik, who have several tattoos.
Tomlinson and Liam Payne joined in the craze on Friday (12Oct12) by copying a two screw design favoured by Styles and Malik, which they had etched on their ankles.
Now they are calling on Horan to get in the tattooist's chair so the whole group has the same design.
Tomlinson tweeted, "So Me and Liam joined the crew yesterday and got two screw tattoo's on our ankles, now we all have it except Niall! Come on NiallOfficial."