Lukaku, 24, was one of the summer’s hottest properties following an impressive four-year spell at Everton, where he bagged 87 goals.
And a potential return to Stamford Bridge, where the Belgian hitman spent four seasons on the books, was heavily mooted before United swooped in to snap him up.
He bagged his first Champions League group stage goal in United’s 3-0 win over Basel on Tuesday night.
As a “reward” for an impressive performance on the pitch, his supporters came up with a novel way to pay their respects to the talented striker.
But the chant – sang along to the tune Made of Stone by Manchester band Stone Roses – contains some rather explicit lyrics.
Lyrics include: “Romelu Lukaku, he's our Belgium scoring genius.
“He's got a 24 inch penis, scoring all the goals, b*****d to his toes.”
But reaction on Twitter doesn’t seem to suggest that everyone is on board with the X-rated tune.
“That's the worst song our fans have come up with. Terrible,” one fan tweeted.
Another said: “Absolutely awful stuff.”
But others saw the funny side, with one person tweeting: “Saw this first thing in the morning and laughed so hard. What amazing creativity.”
With a second saying: “Best fans in the world.”
Lukaku has got off to a strong start at Old Trafford, smashing in four goals in four Premier League games to date.
But former Chelsea ace Graeme Le Saux reckons Lukaku would have performed just as well for the Blues.
He told Starsport: "Romelu Lukaku would score as many goals at Chelsea as he has at Manchester United.
"He is just a consistent goalscorer wherever he goes, he proved that at West Brom, Everton and now United.”
