If you are a seller of thumb tacks (UK: drawing pins) then you "Sell Tacks", which is about how you…read morepronounce Celtic with a Scottish accent, by the way.
Similarly, if you are a SeaLion and you do cool things to impress onlookers, then you do SealTricks.
But seriously, Celtic is one of the great teams of the whole world, let alone the UK. The biggest club in Scotland on every level, playing in a palace of a 60k stadium, which includes a Graveyard so hardcore fans can be buried here! That's how much Celtic means.
First-Hand Experience: this is my fave club in Scotland, and one of my 10 fave clubs in the world. I've seen them live at this stadium many times, I've also seen them away from home at Anfield (Liverpool), other Scottish clubs, and even in Cleveland Browns Stadium facing Boca Juniors. I can't really count the number of times I've watched them play but it's been around a dozen or more. Most recently was 2014. They're a wonderful club with wonderful fans. Being inside Celtic Park is one of the best stadium experiences for any fan anywhere.
Plus they are linked to my fave team Liverpool in many ways and to my mother's homeland of Ireland. So they mean a lot to me. Watching them is a religious experience - and yes that is an in-joke. Since religion is so heavily linked to this club and Rangers.
Celtic (pronounced Seyll-takk in the local accent, and never Kel-tic, ever) are bitter rivals of Rangers, and the religious element means the hatred runs deep. The Irish were always the outcasts and underdogs but when it comes to football they are the big boy.
Rangers has won more Scottish League titles, but Celtic is bigger in every other way. They play in famous green and white hoops. The stadium is in the rough East End of town. I had a gun pointed at me outside their stadium.
Since their first game in 1888, they have never been relegated, which is very impressive, especially now that Rangers were demoted and so Celtic are the only team not to be relegated.
They have won the Scottish League 46 times and are the current champs. They're within 10 of Rangers' record. They've won the Scottish Cup 36 times and the League Cup 15 times.
In 1967 they amazingly became the first British team to win the European Cup, with Manchester United, Liverpool (4 times in a few years) and Nottingham Forest following suit within a decade or so. They were runners up in the 1970 European Cup and in the 2003 UEFA Cup, meaning they have reached 3 major European finals, winning one.
In 67 they had beaten Inter Milan in the final, whereas in 70 they lost to Feyenoord at the San Siro. Their greatest managers include Martin O'Neill who got them to the UEFA Cup Final, and Neil Lennon who got Celtic to a few Champions League knockout phases.
Celtic's club magazine is the oldest in the football world, from 1965.
There are supposedly 9 million Celtic fans around the world including 1 million in the US and Canada. Like Liverpool, they sing "You'll Never Walk Alone" before every game, and they never will.