Here is the full list of all 20 Blackjack of Strip achievements.
Strip the enemy 50 times in a multiplayer game
Unlock a standard deck of cards
Strip the enemy 25 times in a multiplayer game
Unlock a deck of cards with mystical girls
Strip the enemy 10 times in a multiplayer game
Unlock armor
Strip the enemy 5 times in a multiplayer game
Unlock Takashi
Unlock Yumi
Unlock Snow Maiden
Unlock Santa
Unlock a deck of cards with nude girls
Strip the enemy 1 time in a multiplayer game
Unlock Dragon
Win in a single player game 10 times
Unlock Mrs santa
Win in a single player game 5 times
Read the rules in English
Read the rules in Russian
Win in a single player game