Cardiff Troyster is a gambling term for a person who is incredibly good and/or lucky.
They are always in front of the gamewhatever that may be and always have plenty of cash from winning
'Can you believe Mark again!? He came here with $100 and 30minutes later he is winning over $1000, that guy is a Cardiff Troyster'
'I saw a guy in the casino last night who was an all round Cardiff Troyster, he won on everything he played'
A threesome with the act of a male putting his penis between a female's thighs directly under the vagina while penetratingthe third partner (male or female).