You can't always get on with everyone in your workplace.
Admittedly, with many of us working from home at the moment, it is not really an issue - but generally speaking there is likely to be one or two people in the office that sometimes rub you up the wrong way.
The same is true on the football pitch.
Fifteen years ago to the day, football witnessed one of the most memorable on-pitch dust-ups when then Newcastle team-mates Lee Bowyer and Kieron Dyer were sent off for fighting each other.
BBC Sport looks back at that incident as well as four other moments when 'mates' clashed.
Bowyer v Dyer, 2005
Along with Paolo Di Canio pushing over referee Paul Alcock, this was one of the most surprising and shocking moments in Premier League history.
With Newcastle losing 3-0 to Aston Villa at St James' Park and an angry home crowd making their feelings known, frustrations started to show on the pitch.
It all came to a head when Bowyer was left fuming after Dyer decided not to pass to him and a scuffle broke out, with Dyer later admitting he was intentionally not passing to his team-mate.
The fallout from the incident, which resulted in both being sent off, saw Bowyer hit with a seven-game ban while both players were forced to make a public apology for their behaviour.
Batty v Le Saux, 1995
Going back 25 years for this one as, once again, being on the wrong end of a 3-0 scoreline appeared to be the tipping point for two players.
On this occasion it was Blackburn team-mates David Batty and Graeme Le Saux that came to blows.
The incident in question was in Rovers' Champions League game against Spartak Moscow and was the culmination of weeks of simmering tensions between several team-mates, as the unity that had helped them win the Premier League title just a few months earlier appeared to be dissolving.
The moment that led to this on-pitch scuffle was, according to Le Saux's autobiography, when he nutmegged Batty during training.
Then against Spartak both players went for the same ball, ran into each other and a scuffle ensued. Fortunately, big Colin Hendry was on hand to break things up before it got too heated.
Robben v Ribery, 2012
For a period during the mid 2010s, Bayern Munich had one of the deadliest double acts in football, with Arjen Robben and Franck Ribery rampaging down their wings.
It helped that the two were good friends on the pitch but, like every good friendship, there were times when it was tested.
Their one significant flashpoint happened in a Champions League semi-final first leg against Real Madrid back in 2012.
At half time, a heated exchange developed between the two over a decision on who should take a free-kick just before the break. The row continued in the dressing room where Ribery threw a punch at Robben, catching him under the eye.
The fiery encounter did not have a damaging impact on the outcome of the game, however, as Bayern beat Real 2-1 before going on to reach the final, which they lost to Chelsea.
Mitrovic v Kamara, 2019
This one is included for the somewhat bizarre nature of the spat, which started on the pitch and ended in a yoga session.
The initial clash happened in Fulham's Premier League game with Huddersfield in December 2018. With both sides scrapping for survival, the Cottagers were awarded a penalty and the chance to take control of the game.
Aleksandar Mitrovic was Fulham's designated penalty taker but Aboubakar Kamara wrestled the ball off his team-mate and demanded to take the spot-kick.
Tempers flared, Mitrovic backed down and Kamara took the penalty, only to see his effort saved. Mitrovic then spared his team-mate's blushes by scoring a late winner but the two clashed again a couple of weeks later.
In what should have been a calming yoga session, things became heated when Kamara reportedly would not stay quiet, prompting Mitrovic to step in.
It proved to be the final straw for Kamara as he was shipped out on loan soon after.
Fuller v Griffin, 2008
Not quite a full on bust-up but a clash nonetheless, and a bit of an odd one too.
It came during a game between Stoke and West Ham back in 2008. After Carlton Cole scored for the Hammers, having turned Andy Griffin inside out, Ricardo Fuller was about to get the game restarted but suddenly decided that moment - in front of thousands of fans - was the right moment to wander off and have a pop at his captain.
Fuller walked over to Griffin, lambasting him for losing his man, and then fired off a quick slap before his team-mates could intervene and prevent it from escalating.
Unsurprisingly, Fuller was subsequently sent off.