Word game ?-3-?

I didn't really know what to call this, and I hope I can explain it right! I know what I mean!

- I'll start the game with a word. It can be any length. And can include proper nouns. For this example, I will use 'forum'.

- From there, I'll take 3 continuous letters from within that word. It can be any 3, but they have to stay in order, e.g. for, oru, rum
In this case, I will take rum. So we have, forum - rum -

Then I will add a word that contains those 3 letters. Again, those 3 letters must stay in order. The word can be of any length. I'll use 'crumb.'

forum - rum - crumb

The next person uses the last word, in this case, crumb

crumb - umb - number

The next poster uses the last word, number.....