It's the penultimate entry in our Tigers ABC to Z series and the letter Y.Y is for Youngs: It is rare that two sons follow their dad into the Leicester Tigers team – it has only happened with five families in the club’s history.   It is rarer still that those two sons were capped by their country, following in the boots of their father.   But proud dad Nick Youngs has watched his sons Ben and Tom establish themselves at Tigers and play for England, just as he did in his playing days.     Scrum-half Nick scored 71 tries in 145 appearances for Tigers in the 1980s and was capped six times by England, including the 1983 victory over New Zealand at Twickenham.    Ben, also a scrum-half, followed in his dad’s footsteps for club and country, adding a Lions tour in 2013. He has so far made more than 150 appearances Tigers and he and Nick became only the second father and son combination to play 100 games for the club.   Tom, now a hooker after starting his Tigers career as a centre, also toured with the Lions in 2013. He is approaching 100 club appearances and with brother Ben is part of the England training squad preparing for this year’s World Cup.   Y is for yellow cards: The first Tigers player to receive a yellow card was Graham Rowntree after they were introduced in 1995, when they denoted a warning and did not carry a ten minute sin-bin penalty.   Sin bins were introduced in 1997 and Richard Cockerill was the first Tiger to be sent to the cooler against Quins in September 1998.   Martin Johnson was sent to the sin bin 16 times in his Tigers career, more than any other player. Lewis Moody (14), and Martin Corry, Darren Garforth and Graham Rowntree (all nine) are next on the list. Alesana Tuilagi (seven) is the most yellow carded back.