Croix
Aller au devant de quelqu’un avec la croix et la bannière = To receive any one with great fuss and ceremony (often used ironically).
Croquer
Votre enfant est gentil à croquer = Your child is a charming little fellow.
Il croquait le marmot = He was dancing attendance; He was cooling his heels.
[Littré gives as the explanation of this obscure expression that artists while waiting for their patrons used to draw pictures of little monkeys (marmot) in the vestibule. Others assert that in the antechambers of the rich were to be found dishes of cakes in the form of little monkeys, which visitors used to eat (croquer) whilst waiting. But both explanations need confirmation.]
Cru
S’agenouiller à cru = To kneel on the bare ground, on the cold stone (without a hassock or carpet).
[Literally, to kneel on the bare knee, but the quality has passed from the person to the object.]
C’est de son cru = That is of his own creation.