Jaggy thistle

A Jaggy Thistle is a plant that flowers purple on top and is famous for growing in Scotland, as well as a lot of countries all over the world

It's also commonly known as what a true Scotsman has under his kilt

Lassie A: A wunner whit Davie's got oan under his Kilt?
Lassie B: If you ask him he might show you his jaggy thistle
Davie: Haw Darlin', you'll be wantin' tae have a swatchy at ma Scots Bunnet?