Crossed fingers

To cross one's fingers is a hand gesture usually used to wish for luck or to lie/not keep a promise. Early Christians used the gesture to implore the protection of the Holy Cross. The gesture usually called "cross your fingers", "keep your fingers crossed", or just "fingers crossed".

References

1 2 Lee, Linda; Charlton, James (1980). The Hand Book: Interpreting Handshakes, Gestures, Power Signals, and Sexual Signs. Prentice-Hall. ISBN 978-0-13-372425-7. ... crossed fingers are also a sign for good luck , a use that bears much closer resemblance to the original intentions of the cross and that might have accompanied "God be with you."
↑ Orange Coast Magazine. Emmis Communications. May 1990. pg. 177. "In early Christian days, a believer confronted by evil or hostile influences implored the power of the Holy Cross for protection by twisting his middle finger over his forefinger and holding the remaining fingers down with his thumb."
↑ Field Guide to Gestures. Quirk Books. 2003. pg. 201. "Children are a big proponent of this gesture, though they usually use it when telling white lies, believing that having the fingers crossed behind the back makes it okay to fib."
↑ de Lint, Charles (2007). Widdershins. Macmillan. p. 287. ISBN 978-0765312853. Widdershins. Retrieved 2013-05-29. To a child, forget ethics. Crossing your fingers while making a promise truly invalidated the promise.

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[LeeCharlton1980-1] 1 2 Lee, Linda; Charlton, James (1980). The Hand Book: Interpreting Handshakes, Gestures, Power Signals, and Sexual Signs. Prentice-Hall. ISBN 978-0-13-372425-7. ... crossed fingers are also a sign for good luck , a use that bears much closer resemblance to the original intentions of the cross and that might have accompanied "God be with you."

[OC-2] Orange Coast Magazine. Emmis Communications. May 1990. pg. 177. "In early Christian days, a believer confronted by evil or hostile influences implored the power of the Holy Cross for protection by twisting his middle finger over his forefinger and holding the remaining fingers down with his thumb."

[3] Field Guide to Gestures. Quirk Books. 2003. pg. 201. "Children are a big proponent of this gesture, though they usually use it when telling white lies, believing that having the fingers crossed behind the back makes it okay to fib."

[deLint-4] Lint, Charles (2007). Widdershins. Macmillan. p. 287. ISBN 978-0765312853. Widdershins. Retrieved 2013-05-29. To a child, forget ethics. Crossing your fingers while making a promise truly invalidated the promise.