Happened a while back to avoid drawing attention.
Was playing in a DD game, and for whatever reason, things were going better than usual (on the far right side of the curve). Had been playing about 30 minutes, with the pit critter coming over to chat (just me at the table, DD game). He began to notice my pile of chips had grown quite significantly, and had noticed my bets bouncing around with me winning more on the big bets, etc. He once commented about this in fact, which was enough to make me decide to leave at the next shuffle. Count tanked (TC = -5 and dropped farther over the next four rounds) but interestingly I hit 4 snappers in a row, with 4 minimum bets out. He said something like "I had thought you might be counting cards based on your win rate only, but after seeing you get 4 blackjacks in an obviously big + count, with a table min bet out, that's not what you are doing... So what kind of system are you using?" I gave him some gobbledygook about a progression scheme and he walked away (I had lots of boring details to explain to him, naturally. :) )
I particularly liked the comment about "the big + count" which I assume came from seeing all the A/10's showing up for me, when, in fact, the count was terrible.
Of course, mentally I was cursing those 21's since I was winning a grand total of $7.50 per round, rather than the $75 had I had a big bet out.
This is way over a year old so there's little worry about identifying anything. I found it in some old computer notes I was trying to consolidate, and thought I'd pass it on. I won't say for certain, but I don't remember hitting 4 or more 21s in a row at any other time, but it is possible, particularly if they spanned a shuffle where I'd likely not think about it.
The only thing I need to work on in my "act" is that when I get a 21 with a $5 bet out, I should appear to be "happy" when in reality, it sucks with two straws. :)