A McDonalds restaurant in Wales has been forced to issue an apology to its customers, after the it played a sexually explicit rap track to its diners at 9:30am in the morning.

Customers in the Haverfordwest branch of McDonalds in Pembrokeshire were shocked to hear 'Only 17' by US rapper Rucka Rucka Ali being played through speakers while they were attempting to digest their egg McMuffins. The song includes explicit lyrics about underage sex and prison rape. The incident was recounted by Steve Davidson, who told the Metro he heard the track while in the restaurant with his 20-month-old grandson.

"The lyrics are disgusting, they are very explicit – not just a bit risqué or a bit of swearing," he told the tabloid. "It’s not what you want while you’re having your breakfast. You have to be over 18 to download it, for them to be playing it somewhere that attracts children is obviously a concern."

McDonalds blamed the unfortunate incident on a nightshift worker who had left his MP3 player plugged into the speaker system and issued an apology. A representative for the fine dining experience said in a statement: "The vast majority of our restaurants, including Haverfordwest, have external music providers dedicated to creating playlists that have been thoroughly screened for appropriateness of language and content.”

"We apologise to Mr Davidson for this isolated lapse in our rigorous standards."

Listen to the offensive track below (NSFW)

Rucka Rucka Ali seemed pleased with the Welsh exposure, taking to Twitter to celebrate the incident, telling fans: "Tomorrow, there will be youtube videos of Nuckas playing “Only 17” at McDonalds... we're fighting back!!! #FreeRucka."