Say you have a hand where two players see the flop, and they start with the top 25% of hands:

22+ AT+ KT+ QT+ JT+ 54s+ 86s+ Q9s+ K6s+ A2s+

This is 330 combinations out of 1326 possible. Each pocket pair is dealt in six combinations (2c2h 2c2s 2c2d 2h2s 2h2d 2s2d) and there are 13 pairs, so thats a total of 78/330. So each player has a pocket pair 23.6% when they see the flop.

If one of the players has AcTd, the known cards reduces the other player's range to 283 total combos. Of the 78 pocket pair combos from before, TdTc TdTh TdTs AcAs AcAd AcAh are removed, bringing it down to 72 combos. So the other player will have a pocket pair 72/283 or 25.4%.

If one of the players has 5c5d, the known cards reduces the other player's range to 319 combos, 73 of which are pairs, so that's 22.8%.

If one has AcAd, then the other player's range is 277, 73 of which are pairs, so 26.3%.


Long story short, people are more likely to have pocket pairs when you hold big cards, especially aces and kings, because they block more of the non-pp hands than the pp hands.