Plenty of fans took to social media to comment on the presenter's antics, particularly towards the end of the morning programme when Holly told viewers just before the competition segment that she was "desperate for a wee".
After the out-of-character comment, which came just before chef James Martin ended the show with his cooking segment, Twitter was flooded with viewer's comments.
WATCH: Holly Willougby confused fans with odd behaviour on This Morning
It seems that while viewers were confused by the "odd" moments, they were convinced that fellow TV stars Ant and Dec were in fact behind the "prank" as part of their popular "Get Out of Me Ear" segment for Saturday Night Takeaway.
One person wrote on Twitter: "Ant and Dec were in Holly and Phil's ear on #ThisMorning! I want to see James being told it was a prank because it really was uncomfortable to see James trying to stay calm during his segment."
Another viewer said: "This is deffo an @antanddec thing, Holly needing a wee, her and Schofe being really awkward too #thismorning."
Viewers were suspicious of Holly and Phil's behaviour on Monday
Meanwhile, a third wrote: "Mmm has the lovely @antanddec been in the ears of @reallorraine @hollywills & @Schofethis morning? #SaturdayNightTakeaway #thismorning."
Others were convinced that Ant and Dec had taken their tricks to the Loose Women studio, too, after Judi Love was seen jumping up from the desk in a fright after claiming to have seen a spider.
"I'm convinced there is something going on at @ITV studios today!!! Lorraine this morning with cramps, Phil with cramps, Judi with a spider and Jane with cramps!!! Wonder what else is in store!!!", wrote a viewer. Another said: "LOOOOOOL Judi Love screaming live on TV over a spider... I wonder if it's @antanddec #LooseWomen."
This Morning have since hinted that something strange was occuring on Monday. The programme tweeted: "Things got strange during @jamesmartinchef's cookery slot today! Take a look and see what you think... All will become clear this weekend!"
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