[Steve Van Doorn]

# can mean a lot of things now a days.
1. number sign
2. Hashtag
3. Chinese means "well"
4. Viewdata square (unicode)
5. gate
6. grid
7. unequal
8. tic-tac-toe


in my opinion:
two # suggest either "well well(?)" or a two door gate.

[tang-soo]

9. Pound!!!

[Bigg Red]

Or could it be “checkmate”?

From Wikipedia:

Checkmate at the completion of moves is represented by the symbol “#” in standard FIDE notation and PGN.

^^^^
of course, Trump use a double # here.....

[tang-soo]

10. # could mean Sharp

In music, # represents a half tone increase in pitch. For example C# means a half tone above C.