YMMV, but this works for me:
Using Google Chrome, go to Google Images.
Search for the image you want
Select it to enlarge it
Right-click it and select "Open image in new tab" on shortcut menu
Once the new tab has opened, click on it.
Then highlight the URL in the address bar, right-click and select "Copy"
Then come back to CC, open a thread and select "Reply"
In the Reply window, select the "Insert Image" button
Right-click and select "Paste" to paste the image URL into the window that pops up.
The image SHOULD paste into your reply.
I say "YMMV" because I don't know how each person's computer is set up and this method doesn't work well in Internet Explorer. I haven't tried it using Firefox or Safari.