The duo were outside of The Ivy in Los Angeles on Saturday evening when they got into a seemingly aggressive tussle.
Heidi Montag’s husband was pictured locking a distressed Keith, 43, into headlock, before they both fell face-down into a bush.
At first glimpse it seems the Celebrity Juice host and the former The Hills star were playing around, but things appeared to get taken a step too far when Spencer got his arms around Keith’s neck.
Keith seemed to get frustrated with the aggressive situation and was pictured waving his hand at the father-to-be to stop with his efforts.
But Spencer, 33, continued to tackle the alter-ego of Leigh Francis, resulting in them both falling to the ground.
Clearly shaken by the altercation, Keith was left with a glowing red face after screaming for Spencer to stop.
Khloe Kardashian recently called out Amber Rose on Twitter in defence of her little sister, Kylie. Amber had tweeted about Kylie’s relationship with rapper, Tyga, saying: ‘She needs to go to bed at 7 o’clock and relax’ [Getty]
Keith’s quirky outfit, consisting of a crisp white shirt, dark jeans and colourful bum bag was soon creased and dirtied by the pair’s boyish antics.
Meanwhile, Spencer was clad in a garish-print shirt, stone-coloured shorts and trainers.
There was no sign of his wife, Heidi, in the photos, who is currently pregnant with their first child.
Pregnant Heidi, 30, and Spencer Pratt – who found fame on MTV’s The Hills – revealed in an interview with Us Weekly, that they were expecting their first child together earlier this year.
The Celebrity Big Brother stars have recently jetted off on a babymoon to Hawaii, two months before their due date.
Proudly showing off her growing baby bump, the pair looked happier than ever as they enjoyed their short time alone before welcoming their baby boy.