I noticed something about the verbs แตก /tɛɛk/ and หัก /hak/, which both mean 'break'. It's about transitivity.
For those of you who need a simple refresher course, a transitive verb is one which requires a direct object. You have to do it to something. For example, I can lift a box, but I can't just lift (unless it's understood from the context, but that's different).
An intransitive verb is one which does not require a direct object (but you may be able to specify an indirect object using a preposition). For example, I can complain, I can complain to you, but I can't complain you.
Etymologically, หัก is transitive (e.g. I broke the lamp), while แตก is intransitive (e.g. the lamp broke). English uses the same verb in both senses. The English verb is ambitransitive, in linguistics-speak. Thai often has two words where English has just one. Where English has he boiled water vs. the water boiled, Thai has เขาต้มน้ำ vs. น้ำเดือด, (ต้ม /tom/ is transitive and เดือด /dʉat/ is intransitive).
However, หัก has come to be used quite commonly as an intransitive verb. While you can still หัก something, more often you ทำ X หัก ('cause X to break'). This matches the usage of แตก--typically, you ทำ X แตก (also 'cause X to break'). The most common transitive uses of หัก still around are figurative, like หักหลัง, to betray, literally to break (someone's) back; also หักคอ, หักใจ, หักอก, etc. หักอก /hak ok/ is interesting because หักอก means 'break (someone's) heart', while อกหัก /ok hak/ is just as common, meaning ('heartbroken'). This would've been a good one for my Semantic Switcheroo post. Google even turns up a small number of hits for ทำอกหัก 'cause (someone's) heart to break', too. It would appear that หัก is flirting with becoming entirely intransitive.
On the flip side, the traditionally intransitive verb แตก has developed some transitive senses. One in particular seems to be influenced from English. แตกแบงค์ /tɛɛk bɛŋ/ means to 'break a bill', one of the extremely vital services that 7-Eleven provides in Thailand. If you're about to get into a taxi and all you have is a 1000 baht bill (or even a 500 baht bill), you'd better go แตก that แบงค์ at Seven first. In a similar vein, I've also seen แตกวง /tɛɛk woŋ/ meaning 'to break up (a band)', as in 'Aerosmith ทำท่าจะแตกวง' Aerosmith is acting like they're going to break up. The intransitive form is วงแตก /woŋ tɛɛk/, as in 'Potato วงแตกแล้ว' The band Potato broke up.
These are limited uses of แตก as a transitive verb (there are possibly more, like แตกแถว and แตกฝูง, meaning to be different from the pack, or non-conformist), but they're very interesting developments nonetheless.
A kind of transitivity switcheroo.