The chief celebrant at the funeral of Jonny Byrne is calling for an end to the Neknomination craze.
Fr Tom Lalor appealed to young people to say no if they are faced with the social media drinking game.
Hundreds of people are attending the 19-year-old student's requiem mass in Leighlinbridge in Carlow.
He will be buried afterwards in the adjoining cemetery.
Jonathan 'Jonny' Byrne drowned last Saturday night after he jumped into the River Barrow after consuming a quantity of alcohol as part of a Neknomination challenge.
A Neknomination involves a person drinking a pint of beer or spirits in one go - posting a video of the act on online - and nominating others to take on the challenge.
There have been widespread calls for an end to the Neknomination craze in the wake of the tragedy - including an appeal from the Taoiseach Enda Kenny.