Suppress SQL Server Management Studio auto complete

Hit ESC to close the window when done typing the word before hitting space, but if you hit ESC after 'fo' and then type 'o' it will kick in again.

Another option if you don't use it often would be to disable it (Tools->Options->Text Editor->Transact-SQL->General->Auto list members) and use CTRL+J to bring it up manually when you want to use it. Red Gate also has a product called SQL Prompt which might offer more control.

In addition there is an "Intellisense Enabled" option under the Query menu and on the Query toolbar if you want to temporarily disable/enable it.

If you undo (ctrl-Z) after the wrong auto-selection appears, your original entry will be restored.

This will not help with SSMS 2008, but (in case others found this page, like I did), I think I found a solution in SSMS 2014:

Under the Edit pull-down menu, at the bottom, select Intellisense, and then toggle "Complete Word".

This seems to turn off implicit word completion when a space is typed, but I'm still getting the drop-downs offered for completion for columnnames, which can be selected using arrows then return/tab/space.