Trews pattern

[slohairt]

Trews evolved for military purposes in the same way kilts have. Many regiments still wear them. You could look at their websites possibly for pictures.
As for trews just being a "weird" Scots way of spelling a word and pretending it's a different word, that is untrue. Trews is a Lowland Scots adaptation of the Scottish Gaelic word Triubhas meaning trousers.
Lowland Scots (called "Lallans" by native speakers) is not some weird method of phonetic rendering, it is an actual language which differs greatly from standard English. (Many Scottish posters on this site would take you to task for saying that!) Some would argue that it's simply a dialect but most experts agree that it's a separate language in its own right. As for Scottish Gaelic...it's about as close to English as Polish!

Is mise le meas,

Seán Liosliath Ó hAirt

[Planopiper]

Ok, the word 'trousers' is derived from 'trews'. I didn't do the minimum research but now I have. I take back the comment on pretending it's a different word, in this case. But it still pertains to a lot of text I see where people are trying to show how Scottish they are by spelling things phoneticly and using lots of 'ach's and 'ooo's. But that's another topic. It still looks to me like a modern version of the old trews would just be plaid pants.