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Turns out 40 percent of moms fake their reactions to Mother’s Day gifts they don’t like, according to a new survey.

Mother’s Day is this Sunday, and if you’re planning to give your mom something special this year, you may want to pay special attention to her reaction when she opens her gift.

If your mom says “Thank you,” “Awww!,” “I love it,” “Wow, this is great” or “I really needed one of these,” then she might be among the four in 10 of moms who — according to a new survey of 2,000 adults — fake their reactions to Mother’s Day gifts.

MOTHER'S DAY GIFTS YOUR OUTDOORSY, ADVENTUROUS MOM WOULD LOVE

The study, conducted by market researchers OnePoll and commissioned by Groupon, looked at gift-giving habits for Mother’s Day and found that moms are looking for more sentimental presents and time with their family this year.

According to the results, moms want the following for Mother’s Day: something with a sentimental meaning; to be taken out for brunch; a homemade item; a family trip; or a simple card.

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A whole 40 percent of moms will hide their true feelings about a gift they get from their kids, the survey determined. (SWNS/Groupon)

And it’s not only moms who may be scrutinizing your gift choice —your siblings could be trying to one-up you.

It turns out that 66 percent of Americans check in with their siblings to see what they're getting for mom. However, be careful what you share, because 55 percent of those with a brother or sister will deliberately try to give their mom a better gift.

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Even when it comes to filling out the card, 30 percent of participants say they will consider what their siblings write in their cards to ensure they aren’t upstaged in the sentimentality department.

And generally, most people are keeping it short and sweet when it comes to what they write: The average American will put down just 43 words (approximately 2 sentences) in a Mother’s Day card.

The study also found that where you fall in terms of sibling order plays a role in how you approach Mother’s Day. While the average person spends $75, the data showed that it’s the middle child who ends up spending the most on mom.

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The study also found that Americans are grateful for their moms — even if their gifts don't go over as planned. (SWNS/Groupon)

In response to these findings, Groupon has released marketing efforts to help customers find mom an appropriate gift.

In one ad, actress and company spokesperson Tiffany Haddish says, “You know that look you get when mom says, ‘I’m not mad, just disappointed,’?” she asks, before suggesting Groupon for finding a better option, such as taking mom to a restaurant or a show.

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No matter your approach to Mother’s Day, however, one thing was universal from the results — people are really grateful for all that their moms have done for them.

Putting food on the table was the number one thing that Americans were most grateful for when it came to their moms, followed by teaching respect for others, helping to learn manners, showing them how to be kind, doing laundry and exhibiting generosity.