It's Magic, Charlie Brown1981

Charlie Brown:
[after asking Snoopy to make him visible again, Snoopy, unsure how to do it yet, gets a bucket of soapy water, scrubs him down until he's covered from head to toe with soapsuds, then takes the bucket and throws the rest of the water at him, just to watch the suds go away leaving him the same way] A lot of good that did. I'm still invisible, and now I'm all wet.