Sort of, anyway!
Taz has had the cutest little speech impediment -- if you even want to call it that -- substituting /f/ sound for /th/. I really wasn't worried about it; kids usually outgrow such things. I even had a preschool speech therapist once tell me that a lot of the milder speech errors kids make in preschool and kindergarten drop out when they learn to read, due to the emphasis on the actual sounds made by each letter.
Here's where it was really getting in his way: When he was counting, the "fuh-ties" sounded an awful lot like the "foe-ties" and he would often "short-circuit" somewhere in the middle, skipping from, say "fuh-tee fwee" to "foe-tee foe". (I'm still not too worried about that r-w substitution!)
So here's what I decided to try: I pulled out a small mirror, and showed him how the /th/ is a "bite your tongue" sound, whereas /f/ is a "bite your lip" sound. After just a day or two (just a couple of minutes of silly exaggeration each time), he totally "got it" and now bites his tongue with pride whenever he comes across a number with a 3 in it. Not only that, he looks for other opportunities to use the sound correctly -- you should hear him belt out his ordinals! It's also made it easier for him with reading, since we emphasized /th/ as a special case -- he not only correctly sounds out/ pronounces words he sees that include /th/, especially at the beginning, but he's quickly caught on to other digraphs, such as /wh/, /ch/ and /sh/, too!
Little successes like this just make me feel good. :)
Note: After a long career as a preschool special ed teacher, I have tremendous respect for the "magic" that speech therapists are able to accomplish with very young children. Both my little boys, in fact, have benefited directly from professional speech therapy intervention. Little stuff like this probably wouldn't qualify for direct speech therapy; but if a child has a serious speech and language delay, I'd never recommend going at it without the help of a professional. You'd be amazed at what they can do!