The boxer's campmates congratulated him on turning 31 yesterday, and Jennie took the opportunity to craft a makeshift card.
While Amir was away for a swim, the Coronation Street actress made the greeting out of the paper their food rations are delivered in, and got the other celebs to sign it.
"Being thousands of miles away from my family back in Bolton, it is lovely that my jungle family made such a lovely gesture with that card," he smiled.
Jennie got the chance to make his day even more special when she was sent to face the latest Dingo Dollar Challenge with Jamie.
They arrived at a large game of painting-by-numbers, featuring a drawing of a burger and a giant paint palette.
The duo's task was to paint in the picture using the correct colours, according to a key. If the colour they needed wasn't provided, they had to use the other paints to mix it together.
Of course, there was a catch. They only had a giant, double-ended paintbrush, which they had to hold between their legs.
"My painting is not great," Jennie laughed. "I have painted the walls at home before but I’ve then usually got a decorator to come and fix it."
While Jennie did the mixing, Jamie did the painting. "This is the craziest thing I’ve done in my life," he said.
Once they'd obtained the Dingo Dollars, it was off to the Outback Shack, where two birthday treats were on offer: a cake, or jelly and ice cream.
"We could get him back for the strawberries," suggested Jamie, referring to Amir and Iain Lee's 'Strawberry-gate'.
They did the right thing, however, and ordered the cake, with Kiosk Keith calling Croc Creek with the crucial question.
"What is the expected UK household spend at Christmas, £490 or £820?" he asked.
The other three celebs correctly answered the higher amount, and Jamie and Jennie soon arrived back in camp, singing 'Happy Birthday'.
Amir was delighted with his present. "To be honest with you, I’m not a big cake fan, but that cake was amazing," he said.
Iain Lee also loved it, commenting: "Creamy, jammy goodness. It was amazing. I want to marry that cake!"
I'm A Celebrity… Get Me Out Of Here! continues tomorrow at the earlier time of 8.20pm on ITV. The grand final airs on Sunday at 9.00pm.