Gråtrunka is the Swedish term for 'Cryjerking', which is an activity that you can perform when you feel utterly depressed.
For example, after being dumped by your Girlfriend.
Gråtrunk is when you are masturbating while crying.
It is not know why people Gråtrunkar, most probably is that they are trying to ease the pain of the break-up.
Masturbation usually leads to ejaculation, which in this activity usually leads to more crying (and therefore more Gråtrunk).
Gråtrunk is also commonly performed after being rejected by the other sex.
For example, after being denied 'happy time' with the hot girl at the party last weekend.
The activity is commonly performed in the shower while listening to music that makes you even more depressed.
One of the requirements for Gråtrunk is that you are actually crying.
In Sweden, where the activity has many performers every day, The music Group Kent is the most used for Gråtrunk.
Fred got dumped by his Girlfriend yesterday.
He spent the whole night in the shower where he Gråtrunka while listening to 'Bullet for my Valentine'.