The Strawboys is an old tradition in Ireland.
Many years ago when a man and woman got married, it was traditional to hold the wedding breakfast (now known as the wedding reception) in the home of the bride. As the houses of the time were very small and the money was in short supply, only a limited number of friends and neighbours could be invited.
This of course did not go down well with some members of the neighbourhood, as everyone felt that they should have been on the guest list. 
Not to be outdone, these people would gather together in the vicinity of the bride’s home and a decision was made to gate crash the party. In order to disguise themselves they would go into the fields and barns and get some straw and weave it into hats and skirts to cover themselves. As was the norm in those times, everyone could sing, dance or play an instrument; they would set for the bride’s house and invade the party - unannounced.
They would perform in the kitchen of the house and would not leave until they were given a supply from the barrel of stout and some of the wedding cake. Satisfied with this they would then retire to the nearest barn where they would have their own party and enjoy all the fare from the breakfast.
Tradition has it that there was no honeymoon as there is today, but the newlyweds were given the best room in the house to where they retired to after the celebrations.
The Strawboys would then regroup and approach the house where they would commence to play, sing, dance and make as much noise as possible around the outside of the house in order to keep the new man and wife awake for obvious reasons!
The Strawboys of today are usually invited to a wedding for ‘Good Luck’ (by times this invitation being kept a secret from the bride and groom). They will perform a routine during the wedding reception in the hotel. Included in the group will be a Sean Bhean (old woman) and a Sean Fbear (old man) who, during the performance will dance with the new bride and groom and in so doing pass on ‘Long Life and Happiness’ to the young couple.