I’ve been getting increasingly irascible tweets from a friend. Her latest just read, “BREXIT?!?!” She’s also sent me wob (a wavy bob), bacne (acne on your back), consumity (a community of consumers), phygital (digital data made physical), and phablet (a combination of a phone and a tablet).

Lewis Carroll is sometimes blamed for introducing portmanteau words to the language, but he only gave them a name. Linguists call them blends, and they’ve been around for a while in English; words like twiddle (twist + fiddle) go back to the 16th century. “Yes, yes,” says my friend. “But this doesn’t explain why they’re so irritating.”

Perhaps it’s their refusal to play the syntactic game. Other neologisms make use of familiar processes. In English these include compounding, which sticks two existing words together without altering them (photobomb, smartphone, fangirl); derivation, which adds a prefix or suffix to an existing word (tweetable, touchless, forumite, unfollow); and conversion, which borrows an existing word and changes its grammatical class (the noun geek becomes a verb, to geek out; on Facebook, another noun, friend, becomes a verb, to friend someone). You don’t always need to construct a new word at all: hat tip, group hug, date night, first world problem, while still being written separately, function as single lexical items (and warrant dictionary entries of their own).

Words like phablet, jeggings, frenemy and mansplaining bypass all these routes. They’re essentially constructed by jamming two words together and cutting off the bits that stick out. This is related to clipping, where new words are produced by pruning an existing word (nightmare = mare, details = deets). But clippings usually remove entire syllables at a time. Blends aren’t always this principled.

There is some method in their madness. Some blends combine clipping and compounding (jazz + exercise = jazzercise; wedding + admin = wedmin). Others overlap sounds or syllables the two words have in common (alcohol + holiday = alcoholiday; him + bimbo = himbo). And some chop sounds off one or both words and stitch the results together (phone + tablet = phablet, British + exit = Brexit). But it’s quite hard to formulate hard-and-fast rules for them.

Is it this structural unpredictability that makes us trip up over blends? They’re not always infuriating: sometimes we notice them because they’re brilliant. If you’d coined omnishambles, you could probably die happy. So here are some features of the best blends.

1. They’re semantically transparent. It’s pretty easy to work out what a serviceable blend means. Himbo? Yes. Wob? No.

2. They fill lexical gaps in the language. We might not have realised we needed them, but we definitely do. Mansplaining, sexting, chugger? Yes. Phablet? No. (Sometimes a blend gives a name to something so subtle, you need a sizeable circumlocution to define it. I love how people who are obsessed with their Blackberry jokingly call it a Crackberry.)

3. They’re phonologically clever. Anecdata? Yes. What a gorgeous meld of the two words. Stegotortoise? Yes. The vowels in “tortoise” and “-saurus” match perfectly (in my accent, at least). Mompreneur? No. The vowels are different, and it’s not even the right number of syllables. Sexcapade? It squashes a word containing the sounds /ks/ (sex) into one containing /sk/. No wonder I can’t say it.

4. They’re funny. This feature can trump the others. Mankini isn’t phonologically clever, but it neatly encapsulates the abject wrongness of the garment. Sodcasting isn’t semantically transparent (it means playing your music in public so loudly that others can hear it), but it made me laugh out loud; in this case, having to explain it is part of the fun. Bacne? Gosh, no. Spots are not jokes. Please.

5. They give the language more than just a single word. A creative language user divides alcoholic into alc + oholic and bingo, a whole new suffix is born. It’s quite a productive one, too: the Oxford English Dictionary now gives 17 examples of different words ending in –oholic.

In fact, this final process (called backformation) combines many of the above features. It’s semantically transparent. New words like workaholic fill genuine lexical gaps. The phonology of the best examples is pleasing (think about the repeated “o” sounds in shopaholic, chocoholic, and shockaholic). Franken- works in the same way (Frankenfood, Frankenbike), with the added bonus of being funny. And I’m watching the rise of man- as a prefix with a grin: we’ve gone from mansplaining to manspreading and manterrupting.

If nothing else, this list might explain why I shun webinars and go to bed every night hoping for a sleepiphany. And the people I know on Twitter are my friends. Don’t even think about calling them tweeple.