The anti-marijuana ad campaign stoner sloth has gone viral and is getting loads of mockery online.

The ad series features a sloth as a metaphor for a stoner in different situations.

One clip shows a student sloth who fails to answer the test, while another clip shows someone who is too stoned to pass the salt on family dinner. The third one shows a sloth in a party who just couldn't interact with the others and a text that reads "YOU'RE WORSE ON WEED" then appears by the end of each clip.

With the hashtag #stonersloth, this Australian compilation video had more than 1.6 million views on YouTube and became trending on twitter over the weekend.

Smoking Cannabis has been linked to being lazy and less motivated. According to previous studies, long-term use of weed alters the brain's production of dopamine - a feel-good chemical which is also responsible for motivation.

"Dopamine is involved in telling the brain when something exciting is about to happen - be it sex, drugs or rock 'n roll," said Dr Michael Bloomfield, of Imperial College London. "Our findings explain why cannabis has a tendency to make people sit around doing nothing."

With the use of PET (positron emission tomography), the researchers scanned the brains of 38 people - 19 regular cannabis users and 19 non-users. They found out that those who smoked more and those who began smoking pot at a younger age had less dopamine than those who never used pot at all.

"Cannabis is an illegal drug and there is mounting evidence the idea of it being a harmless herb is not true," Dr. Bloomfield added. "When people stop taking cannabis it seems the brain can slowly go back to producing pretty normal levels of dopamine."

"Cannabis has effects on the brain and it's important people can make an informed decision."