I was looking for a keychain that looked like the starbucks tumbler.  I found one that looked ok, but the through hole for mounting to a keychain was just all wrong.

So I created this model from scratch in Blender.  Its a cylinder that is shrunk at one end, then given a knurled effect as seen in this youtube video.

After that, I added a horizontal cylinder that has a round cut for the face.  I tried printing the straw and cup as one model, but it is very fragile and kept breaking off.  So i separated the the straw and left a hole in the cup.  After they are printed, just a drop or two of crazy glue to the hole in the cup and insert the straw.

You can also print the cup and straw completely separately to get a different color for each.  I included 3 stl files (cup and straw, cup only and straw only).

The keychain is just a pack of 50 I got from a random Amazon seller.  It uses an 8mm jump ring to attach the cup to the chain part of the keychain.  A jump ring is an open ring that you bend back together with 2 small pliers.

And as milano stated below, you absolutely want to print this model upside-down.  Its the biggest benefit to having the straw print separately.

I made the hole in the probably a little too big.  As Flashesbuck stated in the comments, you can print the straw by itself a few times (adjusting the xy scaling) to dial in the tube diameter that is appropriate for your printer's tolerances and your slicer settings.