A naggin, a small easily concealed bottle of spirits is the lifeblood of teenage alcoholism and college predrinks in Ireland.
The 200ml bottle of a spirit of your choice (depending on your bank balance at the time of purchase) is the right amount of booze to stop you from getting completely steamed before sneaking off for the bus/luas/cycle into town but also plenty to put you in the perfect state of merriment before a night of debauchery and other shenanigans.
A naggin can be stealthily sneaked into a club or pub that you believe is too expensive, or if you are too broke to keep yourself in drink at a reputable establishment.
A naggin is also deemed an appropriate gift when you do not know what else to buy for the recipient
"I took elocution lessons, at five bob a time, from a genteel old thing in black velvet and musty lace ... who at intervals in our weekly half-hours together would excuse herself and turn aside demurely to steal a swig from a naggin-bottle she kept hidden in her reticule."
The act of sneaking a naggin of vodka into a club for either:
1. The topping up of normal soft drinks (Therefore not having to pay for vodka from the bar)
2. Going into the bathroom and doing shots (usually with someone else) from the bottle until said bottle is gone