When I was growing up, my immigrant parents did an amazing job of learning English, but there were a few words and sounds they just couldn't master. I remember going to the deli counter with my mom as she ordered "one pound of salami, sliced tin" — leaving the butcher looking baffled until one of us kids said "thin," with an overemphasis on the "th" sound my mom couldn't say.

And even today, my dad gets frustrated with those bushy-tailed critters in the backyard that commandeer his bird feeders and eat his tomatoes. He just can't pronounce their name.

He's not alone. On a recent Reddit thread, users weighed in with the English words they found toughest to pronounce. More than 5,500 people posted, sharing words and offbeat pronunciations, personal stories and impossible tongue twisters.

"Squirrel" was a popular submission and seems to particularly cause problems for native German speakers. One user says: "I'd counter from a foreign perspective that 'Squirrel' messes with German exchange students like you wouldn't believe. To be fair though I can't pronounce their word for it either."

(Try it. "Eichhörnchen.")

Carlos Gussenhoven, a phonologist at Radboud University in Netherlands, told Life's Little Mysteries that "squirrel" is a shibboleth, a word notorious for the way its pronunciation identifies its speaker as a foreigner.

Although many non-native English speakers may have trouble with the word, Germans seem to have earned the worst rap with videos gently poking fun at their pronunciation attempts.

From sauce to birds

Popular on the Reddit thread was "Worcestershire," a word that seems to baffle so many speakers, native and non-native alike.

One user offers this handy advice," It's that '-cest-' in the middle that messes people up. If you break it up like worce-ster-shire, the pronunciation makes sense."

Or you could just point to the bottle.

Also popular in the discussion was "penguin." Is this word really that hard to pronounce or was it just an excuse to link to a video of Benedict Cumberbatch voicing a BBC documentary where he said "pengwings" and other interesting iterations of the word?

"I'm completely terrified of the word," Cumberbatch said on "The Graham Norton Show."

Other big contenders

Aside from Worcestershire, squirrel and penguin, here are some of the submissions that popped up often on the Reddit thread of most easily garbled words — along with a few comments from posters.

Choir: "As a foreign speaker: Choir. Seriously. Why?"

wall of drawersDrawer: "Droy-yer. Drar. Droor. Dror. I hate this word."

Anemone: A helpful tongue twister: "In me, many an enemy anemone enema."

Isthmus: From someone who lives in a town where that's the name of the newspaper: "I have no idea how you are supposed to say the word, I just avoid it."

Sixth: "What kind of word is that with an S and xth sound?"

Colonel: "If you know that it's pronounced 'kernel,' it's easy to pronounce. But if you were new to the English language and didn't know that, you would never pronounce it correctly."

Rural: "This one is entirely impossible for me as a German. 'Squirrel' I can manage."

Tongue-twisting trends

"While there are clear trends in words non-native speakers mispronounce (due to irregularities in English spelling), words that are in principle hard to pronounce depend much more heavily on each individual speaker's linguistic background," says Czech linguist and mathematician Jakub Marian, author of "Most Common Mistakes in English."

Words containing an "h" (as in "hello") are difficult to pronounce for native speakers of romance languages and Russian, since there is no "h"-sound in their mother tongues, says Marian, who is fluent in four languages and can get by in four more.

"Words containing a 'th'-sound (either as in 'think' or as in that') are hard for almost everybody apart from Spaniards and Greeks, whose languages are two of the few that contain those sounds," he says.

Marian offers some examples of words that stumble clumsily off a non-native's tongue and why he says they're difficult to say:

lettuce leavesLettuce: Remember that lettuce doesn’t grow on a spruce; and it also doesn’t rhyme with it.

Height: The pronunciation is as if it were written “hight.” The “e” is there just to confuse foreigners.

Fruit: The same situation as in the previous word; simply ignore the “i.”

Comfortable: If you “come for a table” to a furniture shop, it will hopefully be comfortable, although it doesn’t rhyme with it.

Recipe: “Cipe” in this case doesn’t rhyme with “ripe;” it consists of two separate syllables.

Non-native English speakers often cringe when they see anything ending in "-ough." That's because there are at least six pronunciations in American and British English for that relatively innocuous four-letter combination. A poster on StackExchange points out this example: "Though the tough cough and hiccough plough him through…"

Think the English language isn't that tough? Check out "The Chaos" by Gerard Nolst Trenité. This 1922 classic poem is filled with about 800 of the oddest irregularities in English spelling and pronunciations.

Mary Jo DiLonardo Mary Jo writes about everything from health to parenting — and anything that helps explain why her dog does what he does.